Thirty missions.
One connected journey.

Wall Raiser

Frame Command: Raise the Wall

Raise the Wall · 55 min · Ages 10–14

Open lesson 01 — freeOpen 01 — free

Hook

A wall is mostly air, held up by sticks 1½ inches thin — and it is about to face a 150 mph wind. Learn the sticks, count the pounds, and stand your wall in the storm.

Objectives

1. Name plates, studs, kings, jacks, headers, and cripples, and say each job out loud
2. Lay out studs at 16 inches on center so a 48-inch sheet lands on wood
3. Trace 420 lb/ft of roof load down the wall to the ground
4. Explain why a nailed skin stops a wall from racking
5. Read Wall line load, One stud, Header stress, and Lateral ratio

What you build

Bottom plate, studs at 16 on center, kings and jacks, a header, cripples, a double top plate, and a nailed skin.

Nine stages

1. Read & ListenBriefing7 chapters

   Do: Read the seven chapters and say each part name out loud. Look: The wall assembles as you read: plate, studs, the door team, then the skin.

2. Watch It WorkThe Raise6 operations

   Do: Advance the six operations and orbit the wall after each one. Look: Orange load arrows change route when the header lands on its jacks.

3. Knowledge GateProve It6 questions

   Do: Answer six questions. A miss shows why and lets you try again. Look: The finished wall stays on screen so you can check each named part.

4. Guided BuildAssemble6 build steps

   Do: Choose the next correct operation, six times, in build order. Look: The wall grows one piece per correct pick and waits for the right one.

5. Numbers LabCount Itcomputed model

   Do: Move Wall length, Stud spacing, Opening width and Header depth. Look: Header stress climbs with span squared. Lateral ratio climbs with Wall length.

6. InspectorChallenge4 inspector cases

   Do: Inspect four broken walls and name the missing law in each. Look: Cases hide a header, shift a stud, strip the skin, or hang a beam on nails.

7. Stress TestSurvive Itstarts failing

   Do: Start at 150 mph with 6-in nails; get Lateral ratio to 1.00 or less. Look: The wall sways harder as the ratio climbs; the blue arrow is the wind.

8. Your DesignInventyour design

   Do: Pass with the shallowest header and the widest nail spacing you can. Look: Every slider redraws the wall. Header stress and Lateral ratio update live.

9. Public MissionServeone mission

   Do: Find a real framed wall with an adult and label six members. Look: You are looking for the red boxes on the tape at 16, 32 and 48.

Briefing chapters

The Raise

1. Lay the bottom plate on its chalk line — the wall's home address on the slab
2. Stand the two end studs — corners are where walls shake hands
3. March the studs at 16 on center from the left end and count the gaps
4. Frame the door: king studs full height, jack studs as the header's legs
5. Drop the header onto the jacks and set the cripples on top of it
6. Cap the wall with the double top plate, then nail on the OSB skin and walk your work

What the lab computes

Educational figures from the numbers lab, not engineering guidance.

• 1½ × 3½ in — actual size of a nominal 2×4
• 420 lb/ft — Wall line load at 35 psf on a 24-ft house
• 875 psi — allowable header stress for No.2 SPF in the lab
• 2,080 lb — 8 ft of 7/16 OSB at 6-in edge nailing

Vocabulary

stud

A vertical 2×4; actual size 1½ × 3½ in, often precut 92⅝ in tall.

plate

The flat horizontal board at the bottom, and the two stacked at the top.

on center (OC)

Spacing measured from the middle of one stud to the middle of the next.

header

The beam over a door or window that carries the load the missing studs used to carry.

jack stud

The short stud the header sits on; framers also call it a trimmer.

king stud

The full-height stud nailed beside the jack that keeps the opening straight.

cripple

A short stud above a header or below a sill that keeps the 16-in layout going.

racking

A rectangle leaning sideways into a parallelogram under a sideways push.

In the real world

• Every framing tape prints 16, 32, 48 in red boxes, and small black diamonds every 19.2 in for engineered joists.
• Lumber yards sell studs already cut at 92⅝ in: with three 1½-in plates the wall stands 97⅛ in, a ceiling just over 8 ft.
• In Florida and along the Gulf, inspectors check edge-nail spacing on sheathing with a ruler before the siding goes on.

Fun facts

• A crew of three can nail off a 16-ft wall in about four minutes.
• North American builders settled on 16 in so sheets and sticks would always find each other.
• A single stud's footprint is 5¼ in², smaller than your palm, and it carries 560 lb for eighty years.

Serve mission

Twenty minutes with an adult. Find one framed wall you are allowed to look at: a garage, a shed, a basement, a house under construction seen from the sidewalk, or a photograph. Name out loud the plates, a stud, a king, a jack, the header and a cripple. Then measure stud spacing with a tape and find the red boxes at 16, 32 and 48.

Evidence: A photo or sketch with at least six members labeled, one measured stud spacing written on it, and an arrow tracing the load from roof to ground.

Safety: Look and measure only. No active job sites, no ladders, no power tools, and no removing any finish or panel.

Mission brief

Situation. The Academy Shelter needs its first wall: 10 feet long, one doorway, and a roof that weighs 35 pounds on every square foot.

Mission. Raise a wood-framed wall piece by piece, cut a doorway through it that still carries the roof, and prove it holds in a Storm Test.

Why. Every pound on a roof has to reach the ground through wood. If one piece is missing, the drywall cracks, the door binds, or the wall leans in the first gale.

• Every member in place from plate to skin
• Header stress under 875 psi
• Lateral ratio at or under 1.0
• Wall skin on Sheathed, panel edges on studs

Sixteenth Sharp

Measure Command: Make Reality Agree

Make Reality Agree · 40 min · Ages 10–14

Open lesson 02 — freeOpen 02 — free

Hook

One framer, one tape, one tiny 1/16-in mistake repeated 24 times — and the last stud stands 1½ inches off. The hook that wiggles is the honest one. Read a tape to the sixteenth, pull from one datum, and prove a 6×8 frame is square before anyone pours.

Objectives

1. Read a tape to the nearest sixteenth, including marks like 3 7/16
2. Explain why the tape hook slides its own thickness so push and pull both read zero
3. Lay out repeated marks from one datum so small errors do not stack
4. Prove a rectangle is square with equal diagonals and a 3-4-5 triangle
5. Apply the ⅛-in framing tolerance as a labelled rule of thumb

What you build

A bench layout: hook to zero, ten marks from a datum, a 90° check with the square legs, and two diagonals across a 6 × 8 frame.

Nine stages

1. Read & ListenBriefing6 chapters

   Do: Read six chapters. Keep a real tape in your hand if you have one. Look: The bench holds the tape case, tape blade, and board; square legs and two diagonals join later.

2. Watch It WorkThe Raise6 operations

   Do: Step through six operations on the bench, from the hook to the diagonals. Look: Gold ticks are on target. Red ticks have drifted past about 0.12 in. Square legs appear, then two diagonals.

3. Knowledge GateProve It6 questions

   Do: Answer six questions. Convert every fraction to sixteenths first. Look: The label ONE TRUSTED DATUM stays over the board as a reminder.

4. Guided BuildAssemble6 build steps

   Do: Pick the next measuring operation, six times, in true build order. Look: The bench adds the square legs, then the two diagonals, as you go.

5. Numbers LabCount Itcomputed model

   Do: Switch Measurement method, then slide Repeated marks, error, and mismatch. Look: Chained drift is marks × error; a datum uses one error. Ideal 6×8 diagonal stays 10.00 ft.

6. InspectorChallenge4 inspector cases

   Do: Inspect four layouts and name what broke in each one. Look: Case 1's ticks drift red. Case 2's diagonals disagree. Case 3 is a 2-in notch on a 1½-in board.

7. Stress TestSurvive Itstarts failing

   Do: Rescue 24 chained marks at 3/32 in error and a 0.750-in mismatch. Look: Marks 24, Accumulated drift 2.250 in, Diagonal mismatch 0.750 in, Method: chained.

8. Your DesignInventyour design

   Do: Switch Measurement method to One datum, then square the frame. Look: Marks 12, Accumulated drift 0.375 in, Diagonal mismatch 0.500 in, Method: chained.

9. Public MissionServeone mission

   Do: Measure one object three times from the same end, then check its diagonals. Look: Your three readings will differ slightly; that spread is your real tolerance.

Briefing chapters

The Raise

1. Hook the tape on the plate end and feel the tape hook slide to true zero
2. Read the tape blade: whole inches, then the half, quarter, eighth, and sixteenth lines
3. Pull ten gold ticks from one datum on the board and watch them stay gold inside ⅛ in
4. Chain the same ten ticks from mark to mark and watch the far ones turn red as drift passes 0.12 in
5. Set the square legs on the board and prove the corner is 90°
6. Stretch both diagonals and a 3-4-5 triangle across the 6×8 frame — Holds when they agree within ⅛ in

What the lab computes

Educational figures from the numbers lab, not engineering guidance.

• ⅛ in — framing tolerance in the lab, a shop rule of thumb (finish 1/16, concrete ¼)
• 0.625 in — lab Accumulated drift at 10 chained marks of 1/16 in
• 0.375 in — Your Design chained drift at 12 marks of 1/32 in
• 2.250 in — Stress Test chained drift at 24 marks of 3/32 in

Vocabulary

datum

The one trusted point every measurement is pulled from, usually a plate end.

tolerance

How far a measurement may miss and still pass; ⅛ in for framing, a rule of thumb.

nominal

The name size of lumber, like 2×4; the actual size is smaller, 1½ by 3½.

plumb

Exactly vertical, like a hanging string, checked on both faces of a wall.

level

Exactly horizontal, like still water, along a board or a plate.

diagonal check

Measuring corner to corner both ways; equal diagonals mean square corners.

crown

The slight bow along a board's edge; framers turn all crowns the same way.

tape hook

The sliding end clip that cancels its own thickness so push and pull both read zero.

In the real world

• Before a footing is dug, crews stretch strings on batter boards and square them with 3-4-5 and matching diagonals, often to ⅛ in, a field rule of thumb.
• The black diamonds on a tape mark 19.2 in on center — five equal spaces in 8 ft — so each I-joist still lands under a sheet edge.
• Modern crews snap lines with a laser and still check them with a tape and a diagonal, because a laser can drift and a tape does not argue with a 10.00 ft number.

Fun facts

• A tape hook that does not wiggle is the broken one; the slide is how zero stays true.
• The 3-4-5 rule was used by rope-stretchers in ancient Egypt to square fields and temples with knots in a cord.
• Framing a 40-foot wall to 1/16 in is like hitting a 1-inch mark from 640 feet away.

Serve mission

Twenty minutes, a tape, and an adult. Pick one object at home — a door, a tabletop, a window. Hook the tape on the same end each time and measure its width three times, writing each reading to the nearest sixteenth. Then measure both diagonals and decide whether it is square.

Evidence: A dimensioned sketch showing the datum end, three width readings, the spread between them, both diagonals, and your verdict: square or not.

Safety: Let the tape retract slowly with a finger on the blade. The hook corners are sharp. No ladders, and do not measure anything that has to be moved or climbed.

Mission brief

Situation. The Shelter's foundation is poured after this layout. Once the concrete sets, every mark on it is permanent.

Mission. Read a tape to the nearest sixteenth, lay out marks that stay inside ⅛ in, and prove the 6×8 frame is square with its diagonals.

Why. A layout is a promise to every piece that comes after it. Chained errors stack; a datum keeps them small.

• Accumulated drift at or under ⅛ in
• Diagonal mismatch at or under ⅛ in
• Every layout mark pulled from one datum
• Both 6×8 diagonals agree at 10.00 ft

Bridge Builder

Opening Command: Make a Hole That Holds

Make a Hole That Holds · 45 min · Ages 10–14

Open lesson 03 — freeOpen 03 — free

Hook

Above the opening in this mission's wall, 1,260 pounds rest on two short posts. You will size the beam that holds them, then find the header that survives a 5-foot doorway when the usual one reads Doesn't hold yet.

Objectives

1. Tell a rough opening from a finished opening, with the numbers for a 36-in door
2. Name the job of the king, the jack, the header, the rough sill and the cripples
3. Trace 1,260 lb of roof load around the hole and down into the two jacks
4. Explain why doubling a span makes 4 times the bending and 16 times the sag
5. Size a header with a real beam check and choose depth before plies

What you build

One wall with a 36-in opening: king L and king R, jack L and jack R, a two-ply 2×8 header with a ½-in spacer cut RO + 3 in, a rough sill, and cripples above and below.

Nine stages

1. Read & ListenBriefing7 chapters

   Do: Read seven chapters; chapters 5 and 6 hold the two formulas you will use in Count It. Look: The opening frames up beside the text: king L, jack L, header, rough sill, cripples.

2. Watch It WorkThe Raise6 operations

   Do: Advance six operations and orbit the opening after the header lands. Look: The header's ends sit on top of jack L and jack R, not on the kings; the rough sill gets cripple legs.

3. Knowledge GateProve It6 questions

   Do: Answer six questions; two are arithmetic you can do in your head. Look: KING, JACK and HEADER stay labelled on the finished opening.

4. Guided BuildAssemble6 build steps

   Do: Pick the six operations in the order a framer builds them. Look: The wall grows in the order you choose; the header waits for jack L and jack R.

5. Numbers LabCount Itcomputed model

   Do: Slide Line load, Opening span, Header depth, Header plies (2×4 wall). Look: Bending climbs fast with span, Sag climbs faster, and the header reads Doesn't hold yet when the check fails.

6. InspectorChallenge4 inspector cases

   Do: Find the fault in four framed openings before the inspector does. Look: The fault is in the story's numbers as much as in the header, jacks and rough sill.

7. Stress TestSurvive Itstarts failing

   Do: Rescue a 60-in opening at 620 lb/ft from a single 2×8. Look: Bending 1,769 psi Doesn't hold yet; Sag 0.131 in Holds; Reaction / side 1,550 lb with no verdict.

8. Your DesignInventyour design

   Do: Set your own opening and pass the beam check with the least wood. Look: Bending and Sag take color; Reaction / side does not. HUD: beam check clear.

9. Public MissionServeone mission

   Do: Sketch a real opening with five members named and two reaction arrows. Look: In a real frame, the header's ends rest on the jacks; the kings run past them to the top plate.

Briefing chapters

The Raise

1. Mark the rough opening on the bottom plate: 36 in between the jack lines — this lab's Opening span — with king L, king R, jack L and jack R chalked beside it
2. Stand king L and king R full height on each side of the marks, from the bottom plate to the top plate
3. Set jack L and jack R tight against the kings, cut so their tops sit at the header's bottom
4. Land the header on the jacks: two 2×8 plies with a ½-in spacer, cut RO + 3 in so 1½ in bears on each jack
5. Set the rough sill flat across the bottom of the window and stand the lower cripples under it on the 16-in marks
6. Fill above the header with upper cripples on the marks, then cap the wall with the top plate and cap plate

What the lab computes

Educational figures from the numbers lab, not engineering guidance.

• 875 psi — allowable bending stress for No.2 spruce-pine-fir in the lab
• 1,260 lb — roof load on the lab's 36-in header, 630 lb into each jack
• 1,769 psi — Survive It's single 2×8 at 60 in and 620 lb/ft, twice the limit
• RO + 3 in — header length, so 1½ in of it bears on each jack

Vocabulary

rough opening (RO)

The framed hole, bigger than the door or window so the unit and its shims fit.

header

The beam over an opening that carries the load the missing studs used to carry.

jack stud (trimmer)

The short stud the header rests on; framers call it a jack or a trimmer.

king stud

The full-height stud nailed to the jack that keeps the opening straight.

rough sill

The flat 2×4 at the bottom of a window opening, held up by lower cripples.

reaction

The push a support gives back; half the header's load lands on each jack.

bending moment

How hard a beam is being bent; largest at mid-span, M = wL²/8.

ply

One board in a built-up header; two plies plus a ½-in spacer fill a 2×4 wall.

In the real world

• A 16-ft garage door header feels about 28 times the bending of a 3-ft door header under the same roof, which is why it is usually an engineered beam instead of two 2×s.
• A door that sticks only in humid summers often lives under a header that sagged; the swollen door meets the sag at the top corner every August.
• IRC Table R602.7(1) sizes real headers by building width, ground snow load and what the wall carries, so the same 5-ft opening gets a deeper header in snow country.

Fun facts

• The double 2×8 over this mission's 36-in opening works at only 25 % of its strength and sags 6 thousandths of an inch, less than two sheets of paper.
• Framers say jack or trimmer for the same short stud; both words are older than the power saw, and you will hear both on one site.
• Lay a 2×8 flat instead of on edge and it becomes almost 5 times weaker in bending without losing a splinter of wood.

Serve mission

Twenty minutes, a pencil and a tape. Find a door or window you may photograph, or a photo of a house being framed. Draw its opening system: kings, jacks, header, rough sill, cripples. Measure a real door in your home and write its width, then write the rough opening a 36-in door would need (38 × 82½ in, a rule of thumb). Finish with two arrows showing the roof load going around the hole and down the jacks.

Evidence: A labelled sketch with at least five members named, two reaction arrows, one measured door width, and one sentence explaining why the header is cut 3 in longer than the opening.

Safety: Photographs and supervised looking only. Never remove trim, drywall or siding to see framing, and stay off any construction site, even a quiet one.

Mission brief

Situation. The Shelter wall needs a 36-in opening today, and the client is already asking whether a doorway could be 5 feet wide.

Mission. Frame the opening so the roof load travels around the hole and down the jacks, then size the header with a real beam check.

Why. A header that is too shallow sags, sticks the door every humid summer, and cracks the drywall in a diagonal from the corners.

• Header bears on both jacks, cut RO + 3 in
• Bending at or under 875 psi at every span you choose
• Sag within L/240; Header plies (2×4 wall) at 1 or 2
• Every cripple lands on a 16-in layout mark

Handshake Framer

Corner Command: Make Walls Shake Hands

Make Walls Shake Hands · 45 min · Ages 10–14

Open lesson 04 — freeOpen 04 — free

Hook

The coldest square foot in a house is an outside corner: about 10 inches of solid wood with an empty pocket behind it. Rebuild it three ways and find the one that is strong, warm, and gives the drywall something to hold.

Objectives

1. Compare three-stud, California, and ladder-backed corners for backing and insulation access
2. Explain why both drywall edges in a corner need a nailing surface
3. Trace cap-plate laps across intersecting walls and the 24-in splice offset
4. Read the model's 45, 78, and 92% access scores and the 0.35/0.35/0.30 Continuity score
5. Choose a corner that meets an insulation-access target with the least lumber

What you build

Three corner details side by side — three-stud, California, ladder-backed — then a lapped cap plate.

Nine stages

1. Read & ListenBriefing6 chapters

   Do: Read six chapters. Chapter 1 is why the corner frosts in January. Look: Three labelled corners stand side by side: THREE-STUD, CALIFORNIA, LADDER.

2. Watch It WorkThe Raise6 operations

   Do: Advance six operations: two walls, three corner details, then the lap. Look: Watch the extra studs, the flat backer, the ladder blocks, then the cap lap.

3. Knowledge GateProve It6 questions

   Do: Answer six questions about warmth, backing, and the plate lap. Look: The three labelled corners stay on screen while you think.

4. Guided BuildAssemble6 build steps

   Do: Pick six operations in site order: walls, detail, backing, lap, checks. Look: The chosen corner builds first; the lap plate appears when you lap the cap.

5. Numbers LabCount Itcomputed model

   Do: Switch Corner type, Finish backing, and Top-plate lap; set Insulation access target. Look: Access is 45, 78, or 92% by type. Backing stays at 100, 90, or 95%, all Holds. Continuity mixes both with the switches.

6. InspectorChallenge4 inspector cases

   Do: Inspect four corners and name what each one is missing. Look: The model hides the lap plate when Top-plate lap is Open.

7. Stress TestSurvive Itstarts failing

   Do: Warm a Three-stud corner that starts at 45% / 90% access and 51% Continuity score. Look: The two switches lift Continuity score to 81%. Backing stays at 100%, Holds. Access stays 45% until Corner type changes.

8. Your DesignInventyour design

   Do: Start on Three-stud at 85% and find the leanest corner that still passes. Look: Access reads 45% / 85%, Doesn't hold yet. Backing 100% and Continuity score 81% both read Holds.

9. Public MissionServeone mission

   Do: Build two card corners, old and open, and label the pocket and the backing. Look: Notice where the third stud sits: packed in the L, or turned flat as a backer.

Briefing chapters

The Raise

1. Stand Wall A and Wall B at 90 degrees so the end studs and plates form a pocket
2. Nail the three-stud corner: extra studs pack the L and seal the insulation pocket
3. Turn the third stud flat: the California backer opens the cavity to the room
4. Two studs plus ladder blocks at 24 in: the open corner with drywall landings
5. Check both drywall edges have backing within ¾ in of the corner
6. Lap the cap plate across the corner and offset the plate splices 24 in

What the lab computes

Educational figures from the numbers lab, not engineering guidance.

• R-1.25 / in — wood's rule-of-thumb R-value; a 3½-in stud is about R-4
• 45% / 78% / 92% — the model's insulation-access scores for three-stud, California, and ladder-backed
• 24 in — minimum offset between splices in double top plates (IRC R602.3.2)
• 75% Continuity score floor with both switches on; Your Design opens at 85% access

Vocabulary

corner stud

A stud at the end of a wall that another wall is nailed to.

backing

Wood or clips placed so a drywall or sheathing edge has something to fasten to.

California corner

A three-stud corner with the third stud turned flat, leaving the cavity open for insulation.

ladder blocking

Short horizontal blocks between studs, spaced about 24 in, that give drywall a nailing surface.

cap plate

The upper of the two top plates; it laps across the corner onto the next wall.

R-value

How well a material resists heat flow; wood is about R-1.25 per inch.

advanced framing

Framing that removes wood that carries no load so more of the wall is insulation.

top-plate splice

A joint in a top plate; the two plates' joints must sit at least 24 in apart.

In the real world

• Point an infrared camera at a house in winter and every stud and corner shows as a stripe: warmer outside, colder inside.
• Metal drywall clips let framers skip the third corner stud; the drywall edge hangs on the clip, and the cavity stays open.
• Many energy codes now credit advanced-framing corners because that is where insulation used to be skipped.

Fun facts

• About a quarter of a conventional wall's area is wood, not insulation; advanced framing brings that toward a sixth, a rule of thumb.
• The 24-in splice offset means the two top plates never share a weak spot, so a cut in one is bridged by the other.
• Frost on an inside corner is a thermal photo of the framing behind the paint.

Serve mission

Twenty minutes, card and school glue. Build a corner of two cardboard walls, each about 8 inches tall, with strips of card for studs. Make it the old way with three 'studs', then rebuild it as a California corner with the third stud turned flat. Show an adult where the insulation pocket was and where each drywall edge would be nailed. If you have time, add a third version with ladder blocks.

Evidence: Two photos or drawings, old corner and open corner, with the pocket, the backing, and the plate lap labeled.

Safety: Card and school glue only. An adult does any cutting with a knife. No lumber, no fasteners, no climbing to look at a real corner from a ladder.

Mission brief

Situation. The Shelter's first two walls are up, and they meet at a corner that will face north wind every winter.

Mission. Join the walls so they act as one box, give both drywall edges backing, keep the cavity open for insulation, and lap the plates.

Why. A corner that is only solid wood frosts inside in January. A corner that is not lapped or backed cracks and separates.

• Finish backing Complete and cap plates Lapped
• Continuity score 75% or better
• Insulation access at or above the target
• Both drywall edges land on wood or clips

Box Locker

Skin Command: Lock the Box

Lock the Box · 45 min · Ages 10–14

Open lesson 05 — freeOpen 05 — free

Hook

Right now one person can push your wall over. Nail two sheets on and it holds two thousand pounds of wind. The secret is in the nails, not the sheets.

Objectives

1. Explain why a nailed sheet stops a frame from racking
2. Lay sheets so every edge lands on a stud, a plate or a block
3. Read wall capacity from the edge-nail spacing: 260, 380 or 490 plf
4. Cut a window opening to its corners without weakening the sheet
5. Tell structure from weather: sheathing stiffens, house wrap keeps it dry

What you build

Two 4×8 sheets of 7/16 OSB on a 10-ft wall, a stud behind the centre joint, a window cut to its corners, and edge nails at 6, 4 or 3 in.

Nine stages

1. Read & ListenBriefing6 chapters

   Do: Read six chapters; chapter 4 holds the three numbers the Stress Test turns on. Look: Two 4×8 panels sit on the 10-ft frame; STRUCTURAL SKIN labels the sheets and the header shows in the window.

2. Watch It WorkThe Raise6 operations

   Do: Advance six beats; push the frame in beat 1 and again in beat 6. Look: Nail rows line each panel edge; a stud backs the centre joint; the window cut stops at the jacks.

3. Knowledge GateProve It6 questions

   Do: Answer six questions; one of them is squared arithmetic. Look: The sheathed wall stays on screen; nail rows, the joint stud and the window cut are clues.

4. Guided BuildAssemble6 build steps

   Do: Put six operations in order, from the square corner to the final walk-through. Look: Sheet 1 stands on the bottom plate; sheet 2 leaves a ⅛-in gap; nails and the window cut follow.

5. Numbers LabCount Itcomputed model

   Do: Set Wind speed and Panel coverage; pick Edge fastener spacing; flip Panel joints. Look: Lab start: Wind demand 1,065 lb, Wall capacity 2,080 lb, ratio 0.51. Capacity jumps at 4 in and 3 in.

6. InspectorChallenge4 inspector cases

   Do: Inspect four sheathed walls and name the law each one broke. Look: The prompt tells you where the nails and the cuts went; the model shows the joint.

7. Stress TestSurvive Itstarts failing

   Do: Hold a 150-mph gust by choosing the right Edge fastener spacing. Look: Demand / capacity reads 1.15 at 6 in, 0.79 at 4 in and 0.61 at 3 in.

8. Your DesignInventyour design

   Do: Pick the wind and the layout, then pass with the widest nail spacing that works. Look: You open at 2,726 vs 2,080 lb, ratio 1.31. Demand / capacity reads Holds at 1.0 or under.

9. Public MissionServeone mission

   Do: Test three craft-stick frames: bare, one diagonal, and card-sheathed. Look: The card frame barely moves; the bare one folds into a parallelogram.

Briefing chapters

The Raise

1. Push the bare frame: studs, plates and the header rack into a parallelogram, and the red diagonal grows
2. Stand the first 4×8 OSB sheet on the bottom plate, flush with the corner stud
3. Land the vertical joint on the centre of a stud, with ¾ in of wood for each sheet
4. Set the second sheet with a ⅛-in gap; edge nails at 6 in, field nails at 12 in
5. Cut the window opening out of the sheet exactly to the jack studs at its corners
6. Push again: the box is locked and the red diagonal shrinks to nothing

What the lab computes

Educational figures from the numbers lab, not engineering guidance.

• 260 plf — allowable shear for 7/16 OSB with 8d nails at 6 in along the edges
• 490 plf — the same sheet with edge nails at 3 in, nearly double
• ⅛ in — the gap between sheets so wet OSB can swell without buckling
• 2.25× — the extra wind push at 150 mph compared with 100 mph

Vocabulary

sheathing

The structural sheets, OSB or plywood, nailed over the studs.

shear wall

A sheathed wall built to resist sideways force.

racking

A rectangle leaning into a parallelogram under a sideways push.

edge nailing

Nails around the perimeter of a sheet; they carry the shear.

field nailing

Nails across the middle of a sheet; they only hold it flat.

blocking

Short pieces of lumber nailed between studs to back a sheet edge.

water-resistive barrier

House wrap or felt over the sheathing that sheds rain to the outside.

OSB

Oriented strand board: wood flakes glued in layers into a 4×8 sheet.

In the real world

• Inspectors in hurricane country check sheathing nail spacing with a ruler and look for sunk nail heads before the house wrap goes on.
• Many older houses have a 1×4 let-in brace notched into the studs at 45 degrees instead of sheathing: one diagonal, one triangle, one direction.
• Framers set the ⅛-in gap between sheets by laying an 8d nail flat on the edge, pushing the next sheet against it, and pulling the nail out.

Fun facts

• Some OSB is sold sized for spacing, 47⅞ by 95⅞ inches, so the ⅛-in gap appears on its own when the sheets sit on a 48-in layout.
• Nailing at 3 in instead of 6 in nearly doubles a wall's sideways strength without changing a single stick of lumber.
• Wind push grows with speed squared, so a 150-mph gust shoves 2¼ times harder than a 100-mph one, not 1½.

Serve mission

About 20 minutes at a table. Build three small rectangles from craft sticks and school glue, each about 6 by 4 inches, with the sticks overlapping at the corners. Leave the first one bare. Glue one diagonal stick across the second, corner to corner. Glue a rectangle of cereal-box card across the whole face of the third, like sheathing, with a dab of glue every inch along the edges. Let everything dry. Then stand each frame on the table, push its top corner gently sideways with one finger until it starts to lean, and measure how far the top moved. Write the three numbers down.

Evidence: A photo of the three frames side by side, or a table with three rows, bare, diagonal and card, showing how far each top corner moved in inches.

Safety: Craft sticks, school glue and cereal-box card only. An adult does any cutting. Wait for the glue to dry before testing, and push gently; the point is to measure, not to break things.

Mission brief

Situation. The Shelter's first wall stands, but every gust makes it sway. The forecast says 150 mph.

Mission. Sheathe the wall so every edge lands on wood, cut the window without weakening it, and pick the nail spacing that keeps Demand / capacity at or under 1.0.

Why. A bare frame racks. A nailed skin turns it into a shear wall. Edge nails carry the force, and wherever an edge floats, the sheet does nothing.

• Every panel joint reads Backed
• At least two sheets on the wall
• Demand / capacity at or under 1.0 at 150 mph
• Window cut to its corners, never past them

Box Squarer

Room Command: Raise the First Room

Raise the First Room · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

Four perfect walls, one wrong room: the corner was an inch out and the cabinets did not fit. A rhombus has four equal sides too. Raise the Shelter's first room and prove it square with two tapes.

Objectives

1. Snap a room from the floor-plan contract before any wall stands
2. Raise, brace, and plumb each wall in two directions
3. Square a rectangle with equal diagonals (12 × 16 → 20.00 ft)
4. Straighten the top plate with a string-and-blocks check
5. Tie corners and lap cap plates so four walls become one box

What you build

Four perfect walls can still make a diamond. Raise the Shelter's first 12-by-16 room, pull both diagonals to 20.00 ft, and lock the corners into one box.

Nine stages

1. Read & ListenBriefing6 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 20.00 ft — Ideal diagonal of the 12 × 16 ft Shelter room (24.41 ft at 14 × 20)
• ¼ in — Academy target for Diagonal mismatch and Top offset
• 1.13 in — Stress Test Top offset, ⅜ in per 32 in of height on an 8-ft wall
• 400 lb — rule of thumb for a sheathed 16-ft 2×4 wall

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Land Reader

Site Command: Read the Land

Read the Land · 45 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

Same building, same hill, three futures: a flooded door, a slamming door, or a quiet bench in the sun. Read the contours, follow the water and the sun, and choose where the Academy Shelter stands.

Objectives

1. Read contour interval and spacing to judge slope as rise over run
2. Trace runoff: water crosses contours at right angles, and a valley V points uphill
3. Compare drainage, sun, wind, access, and setbacks across three candidate pads
4. Score a pad from the survey team's ratings, your priorities, and a steep-slope penalty
5. Choose a location that reaches a 72 % composite with Local slope at or under 15 %

What you build

Same hillside, three futures: a flooded valley, a windy ridge, a bench at 8 %. Read contours, follow water and sun, and pick a pad you can defend.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 2 ft — contour interval on this site plan
• 72 % — Composite score the chosen pad must reach
• 15 % — Local slope must be at or under this to pass
• 27,000 gal — one inch of rain on one acre

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Water Guide

Grade Command: Give Water a Way Home

Give Water a Way Home · 45 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

One inch of rain sends about 623 gallons through a house's downspouts. A lawn that leans the wrong way pours it into the basement. Shape the ground so every drop has a way home.

Objectives

1. Compute slope as fall divided by run, converting inches to feet first
2. State the code rule: 6 in of fall in the first 10 ft from a foundation
3. Tell a swale from a ditch and explain why wide and shallow wins
4. Predict ponding at any low point that has no outlet
5. Explain how slope, rain and ground cover together set the erosion index

What you build

Shape the ground around the Shelter so every drop has a way home: six inches of fall in ten feet, a grassy swale to an open outlet, and a cloudburst to prove it.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 5 % — the code minimum next to a foundation: 6 in of fall in the first 10 ft (IRC R401.3)
• 2.50 % — Numbers Lab slope at 6 in over 20 ft; Outlet starts Blocked
• 623 gal — one inch of rain on a 1,000 ft² roof
• 0.12 — the Erosion index the site must stay under in the cloudburst

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Ground Truth

Soil Command: Know What Holds You

Know What Holds You · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

A crack climbed a bedroom wall because one corner of the house sat on an old creek bed. Everything you build stands on soil — find out what it can hold before it decides for you.

Objectives

1. Name the soil layers from topsoil down to gravel and tell them apart by grain size
2. Compute average bearing pressure as load divided by bearing area, in psf
3. Read the code's presumptive bearing table: clay 1,500, sand 2,000, gravel 3,000 psf
4. Explain why differential settlement cracks walls and how water and frost make it worse
5. Use Bearing area, Compaction index and Soil model to bring Average pressure and Settlement index into limits

What you build

Cut the ground open, run the jar test, and push 12,000 lb onto a footing to learn what clay, sand and gravel can carry before the house decides for you.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 1,500 psf — Average pressure from 12,000 lb on an 8 ft² footing (lab Sand)
• 1,200 / 2,000 / 3,000 psf — Educational limits for Clay, Sand and Gravel
• 2.77 — Clay invent Settlement index; Holds is at or under 1.0
• ½ in over 20 ft — rule of thumb for differential settlement that cracks walls

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Weight Spreader

Footing Command: Spread the Weight

Spread the Weight · 55 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

A porch post pushes 530 pounds on every square inch of its own end, and the soil under it can take about 10. Pour the footing that turns 530 into 7. Then find out why the post has to stand in the middle third.

Objectives

1. Explain how a footing turns a post's 530 psi into about 7 psi on the soil
2. Size a footing from load ÷ allowable bearing pressure and round it up
3. Keep the post inside the middle third and predict the Max edge pressure
4. Place rebar where concrete stretches, with 3 in of cover against earth
5. Recite the small footing rules: 6 in thick, 12 in deep, below the frost line

What you build

A porch post presses 530 psi on its own end; clay can take about 10. Pour the footing that spreads 16,000 lb to 7 psi, keep the post in the middle third, and pass a 24,000-lb test.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 10.7 ft² — required area for 16,000 lb on clay rated 1,500 psf
• L ÷ 6 — the middle-third limit; 8 in either way on a 4-ft footing
• 2,288 psf — Max edge pressure in the Stress Test (allowance 1,875)
• 3 in — concrete cover for rebar cast against the earth

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Level Deck

Platform Command: Build the Floor

Build the Floor · 55 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

Every floor you have ever jumped on is a row of tiny bridges, and each one was chosen with a formula you can do in your head. Today you pick the joists for the Academy Shelter and discover why the deep board beats the wide one three times over.

Objectives

1. Trace a floor load from the subfloor through joists, rim boards, and supports to the ground
2. Turn a floor pressure in psf into a joist line load and bending with M = wL² ÷ 8
3. Predict how depth (cubed) and span (to the fourth) change sag, and check it against L/360
4. Explain why rim boards, blocking, and supported panel edges stop rolling joists and squeaks
5. Compare a raised joist platform with a 3½-inch slab-on-grade and name gravel, vapor sheet, and slab

What you build

Frame the floor everyone will stand on: posts, rim boards, joists at 16 inches, blocking, subfloor. Then load it with a birthday party and learn why the deep board wins.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 66.7 lb/ft — Joist line load at 50 psf × 16 in on center (gauge 67)
• 875 psi — allowable bending stress for No.2 SPF (teaching value)
• L/360 — floor sag limit (IRC R301.7)
• 1.8× — stiffness gain from a 2×10 to a 2×12

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Tied Down

Anchor Command: Tie It Down

Tie It Down · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

Inspectors have found whole houses sitting four inches off their foundations after a storm, walls fine, roof fine, bolts missing. Wind cannot slide a house that is tied down, and it cannot tip a wall that is held at the end. Today you bolt the Academy Shelter to the earth in all three directions.

Objectives

1. Trace the load path from roof to soil and name the connector at every joint
2. Turn wind speed into pressure with q = 0.00256 × V² and see why 165 mph nearly doubles 120
3. Tell the three jobs apart: bolts against sliding, hold-downs against overturning, both against uplift
4. Apply the builders' bolt rules: half-inch, 7 in deep, 6 ft apart, two per plate, one within 12 in of each end
5. Read Sliding demand, Anchors / capacity, Hold-down tension, and Uplift estimate, and keep demand under capacity

What you build

Bolt the Academy Shelter to the earth. Wind pushes, lifts and tips a wall all at once; you set the sill, the bolts and the hold-downs, then prove the load path holds at 120 mph.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 0.00256 × V² — wind speed in mph to pressure in psf; 120 mph is 36.9 psf
• 6 ft — the most a builder may leave between sill anchor bolts (IRC R403.1.6)
• 12 in — a bolt must sit within this distance of every plate end
• 4,999 lb — hold-down tension in the lab at 120 mph, on a 5,250-lb bracket

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Triangle Locked

Triangle Command: Why Roofs Stand

Why Roofs Stand · 45 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

Pin four sticks into a square and it folds at a touch. Pin three into a triangle and you cannot move it. That is the whole secret of roofs, and today you find out why the board that stops your walls from spreading is on the ceiling, not high in the attic.

Objectives

1. Explain why a pinned triangle cannot fold while a square of the same sticks can
2. Read Roof angle, Rafter / joint, Outward thrust, and Closed triangle and say what each means
3. Tell a rafter tie at the plate line from a collar tie in the top third
4. Predict how raising Roof rise cuts Outward thrust in the peak-load case
5. Close the force triangle with Bottom tie Installed, Triangulation Braced, and Joint quality at least 70 percent

What you build

Pin a square and it folds; pin a triangle and it locks. Close the Shelter roof so 6,000 pounds at the peak squeeze the rafters and cannot shove the walls apart.

Nine stages

1. Read & ListenBriefing6 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 26.6° — Roof angle at 20 ft span and 5 ft rise, a 6-in-12 roof
• 6,000 lb — lab Outward thrust at 6,000 lb peak load, about a pickup
• 6,708 lb — lab rafter compression printed on Rafter / joint
• 0.67 — span factor for a rafter tie raised one-third, a rafter-span table footnote

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Rise Over Run

Pitch Command: Rise, Run & Angle

Rise, Run & Angle · 45 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

There is a number stamped on every carpenter's square that lets a crew cut forty rafters without a calculator. Today you learn what 13.42 means, and why a roof you can see from the street is bigger than the house underneath it.

Objectives

1. Convert a pitch ratio to an angle with atan(rise ÷ run)
2. Measure run to the ridge face, then add the sloped tail to Common rafter
3. Compare Two-slope area to the plan using 1 ÷ cos θ
4. Read Roof angle, Common rafter, Two-slope area, Drainage index, and Overhang
5. Keep Roof pitch at or above 3:12, Overhang at or under 3 ft, and Drainage index at or above Drainage target

What you build

Stamp 6:12 on the shelter, turn rise and run into an angle and a 15.02-ft rafter, and watch the roof grow bigger than the house underneath it.

Nine stages

1. Read & ListenBriefing6 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 13.42 in — common-rafter length per foot of run at 6:12
• 26.6° — Roof angle the lab prints at 6:12
• 11.9375 ft — run to the ridge face on a 24-ft span with a 2× ridge
• 1.41× — sloped-area factor at 12:12 (plan area ÷ cos θ)

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Seat and Heel

Rafter Command: Cut the Birdsmouth

Cut the Birdsmouth · 55 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

Every rafter in your house has a bite taken out of it shaped like an open beak, and the angles were drawn with a square, not taped. Today you cut the birdsmouth on a true-scale 2×10 and learn the quarter rule that keeps it from splitting.

Objectives

1. Name the seat cut, heel cut, plumb cut, tail, and HAP on a common rafter
2. Derive seat and heel lengths from notch depth and pitch: seat = notch ÷ sin θ
3. Apply the quarter rule (end notch ≤ D/4) and full seat on a plate ≥ 1½ in
4. Explain why every rafter must share one HAP from one pattern rafter
5. Measure run to the ridge face so Rafter length lands on stock lumber

What you build

Cut a true-scale 2×10 birdsmouth: seat level on the plate, heel plumb, notch under a quarter of the depth, and one HAP for every rafter on the roof.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 9¼ in — actual depth of a 2×10
• 2.31 in — deepest legal end notch on a 2×10 (D/4)
• 4.55 in — lab seat cut for a 2.035-in notch at 6:12
• 8.07 in — lab HAP at 22 percent notch, 6:12

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Web Reader

Truss Command: Forces in a Web

Forces in a Web · 55 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

The roof over most new houses was built flat on a factory table out of 2×4s you could bend by hand, then lifted on by crane. Today you build one, read every push and pull inside it, and learn the one rule every trade on the site obeys: never cut a truss.

Objectives

1. Name top chord, bottom chord, web, panel point, heel, and bearing on the model
2. Read Top chord / joint 8,944 lb · 90%, Bottom-chord tension 8,000 lb, and Web force index 1,800 lb
3. Explain why loads belong at panel points and why a zero-force web still stays
4. Apply IRC R802.10.4: never cut, drill, or notch a truss without a sealed repair
5. Keep Top chord / joint, Bottom-chord tension, and Web force index at Holds with Geometry Symmetric and Web system Complete

What you build

Build a factory roof truss from 2×4s and toothed steel plates, read every push and pull, and keep the one rule every trade obeys: never cut a truss.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 24 in — standard factory roof-truss spacing
• 8,944 lb — lab top-chord compression at 8,000 lb peak load on a 24-ft 6:12 truss
• 20 gauge — typical gusset-plate steel
• R802.10.4 — the IRC do-not-alter rule for trusses

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Downhill Lapper

Roof Skin Command: Drain the Sky

Drain the Sky · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

One inch of rain dumps 623 gallons on a thousand-square-foot roof, and every drop is looking for one lap that faces the wrong way. Today you layer the Academy Shelter like fish scales, then find the one edge where the rule flips.

Objectives

1. Name the roof drainage layers from deck to outlet and the order they go on
2. Explain shingle-style lapping: lower piece first, each upper course overlapping downhill
3. Tell eave drip edge from rake drip edge and why the install order flips
4. Read Leak-risk index and fix a short lap, a missing detail, or a blocked outlet
5. Recognize valleys, ridges, ice barriers, and penetrations as concentrated-flow details

What you build

Layer the Shelter's roof like fish scales: deck, drip edge, underlayment, shingles, valley, ridge. Then rain-test 623 gallons downhill to an open gutter.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 623 gal — one inch of rain on 1,000 ft²
• 2 in — minimum underlayment lap on 4:12 and steeper (the lab's gate is 4 in)
• 5 in — three-tab shingle exposure (rule of thumb; 12 in tall, 2 in headlap)
• 0.08 — teaching Leak-risk index the lab must stay under; the default opens at 0.14

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Roof Keeper

Storm Command: Keep the Roof On

Keep the Roof On · 60 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

Wind does not push a roof off — it lifts it like a lid, and at 130 mph the lab's little roof feels the pull of thirteen cars. Today you build the chain of steel and nails that keeps the Academy Shelter's roof on, and find out why an open garage door can lose you the whole thing.

Objectives

1. Turn wind speed into roof uplift with q = 0.00256 × V² and the lab's single 1.4 factor
2. Trace the uplift chain from sheathing through hurricane ties, the wall diaphragm, and base anchors to the soil
3. Compare Roof-tie count and Capacity per tie with Uplift demand, and keep Demand / capacity at or below 1.00
4. Explain why corners, eaves, and overhangs raise the lift, and why a failed opening adds inside push
5. Read the four lab gauges and say when Path continuity is Complete

What you build

Wind lifts a roof like a lid. Strap the Academy Shelter from shingle to soil, read 26,469 lb of lift at 130 mph, and keep every link of the chain stronger than the storm.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 43.3 psf — velocity pressure at 130 mph (q = 0.00256 × V²)
• 26,469 lb — lab roof uplift at 130 mph, about thirteen cars
• 415 lb — a light hurricane tie's allowable uplift
• 0.55 — internal pressure factor once a door or window fails

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Dry Sill

Window Command: Open Without Leaking

Open Without Leaking · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

You spent eighteen lessons keeping water out of a wall, and now you cut a hole in it on purpose. The 36-by-48 window has 168 inches of joint. Flash it so every drop that sneaks in finds the way out, and learn the one edge you must never seal.

Objectives

1. Check a rough opening's clearance and diagonals, and use Frame distortion as the squareness lever
2. Sequence the sill pan, window, jamb flashing, and head flashing so every layer sheds downhill
3. Explain why the bottom flange stays open so the pan can weep
4. Shim and fasten a window without racking the frame or blocking drainage
5. Diagnose reverse laps, blocked outlets, flat pans, and bowed frames with Leak-risk index

What you build

Flash a 36-by-48 window so 168 inches of joint drain: sloped sill pan, window on shims, jambs over the flange, head over the jambs, bottom left open to weep.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 168 in — joint length around a 36 × 48 window
• ½–¾ in — rough-opening clearance each way (builders' rule)
• 1 in 10 — sill-pan slope, about 6°, builders' range 5–10°
• 4–6 in — flashing tape width

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Even Reveal

Door Command: Square, Plumb & Seal

Square, Plumb & Seal · 55 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

A door that closes by itself is not haunted — it is telling you exactly which way the hinge jamb leans. Today you hang the Academy Shelter's front door so it swings true, reads an even eighth-inch gap all round, and still closes with two fingers.

Objectives

1. Set the hinge jamb plumb in two directions and hang the door from that axis
2. Read even ⅛-inch reveals and equal diagonals as proof the frame is square
3. Shim behind each hinge, drive one 3-inch screw into the jack stud, and support the threshold
4. Tune weatherstrip and sweep near 60 percent compression so the door seals without a shove
5. Diagnose a ghost door, a racked frame, a bouncing threshold, and a two-hand latch

What you build

Hang the Academy Shelter's front door so it swings true, reads an even eighth-inch reveal, drains at the threshold, and still latches with two fingers.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 32 in — clear width of the required egress door (IRC R311.2)
• ⅛ in — a good reveal all round, builders' rule
• 87.7 in — diagonal of a 36 × 80 opening
• 3 in — the hinge screw that reaches the jack stud

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Watershed Warden

Flashing Command: Give Water a Path

Give Water a Path · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

One inch of rain drops about 623 gallons on a small roof, and every gallon is looking for the single lap you got backwards. Today you build the metal-and-membrane maze that sends all of it home. Then you reverse one piece on purpose and watch where the water goes.

Objectives

1. State the shingle rule: every upper layer drains over the layer below
2. Weave step flashing, one L-piece per roof course, at a roof-to-wall
3. Place a kickout that throws roof water into the gutter, not the wall
4. Leave a 2-inch drying gap between siding and roofing
5. Integrate a vent-pipe boot: uphill half under, downhill half over

What you build

Weave step flashing, a kickout, and a pipe boot on a roof-to-wall so rain still drains over every lower layer, then reverse one lap and watch it fail.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 4.0 in — Step-flashing lap the lab requires (teaching target)
• 2.0 in — Wall clearance that brings the gauge to Holds
• 0.08 — Leak-risk index pass line (educational comparison)
• 623 gal — one inch of rain on a 1,000 ft² roof

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Boundary Tracer

Air Command: Stop the Invisible Leaks

Stop the Invisible Leaks · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

Your house is breathing right now — warm air out the top, cold air in at the ankles — and every crack adds up to a hole you could push a golf ball through. Today you make the invisible wind visible with a blower door and smoke, then shut it off one hole at a time.

Objectives

1. Trace one continuous air barrier around the conditioned space without lifting the pencil
2. Turn a 50 Pa blower-door cfm into ACH50 with cfm × 60 ÷ volume
3. Seal the five families in order: base, roof, seams, openings, penetrations
4. Read Effective leak area, Pressure airflow, and Air changes @ 50 Pa (ACH50); hit 45 cfm and 2.25 /h
5. Tell accidental leakage from designed ventilation, and why a tight house still needs a fan

What you build

Your house is breathing through a golf-ball hole you cannot see. Trace one air-barrier line, seal the five leak families, and close Pressure airflow to 41.7 cfm at 50 Pa.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 50 Pa — blower-door test pressure, about a 20 mph wind on every wall (rule of thumb)
• 21.6 cm² — lab Effective leak area with all five families sealed at 120 cm² base
• 2.25 /h — Air changes @ 50 Pa (ACH50) pass line, tighter than the 2021 IECC's 3 ACH50 in zones 3–8
• 1.9310 cfm per cm² — blower-door flow constant at 50 Pa

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Thermal Cartographer

Heat Command: Slow Energy Down

Slow Energy Down · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

A wall full of R-19 insulation is really an R-14 wall, because the studs are zippers on a puffy jacket. Tonight it is going to −5 °F, the air inside is wet, and somewhere in a corner a surface is about to start sweating. Find it before the water does.

Objectives

1. Relate R-value and U-factor, and read Whole-wall U as the mixed wall
2. Spot framing thermal bridges: studs, plates, headers, and three-stud corners
3. Compare cavity batts with continuous insulation that crosses the bridges
4. Connect Inside surface, Coldest spot (corner), and Indoor dew point to condensation risk
5. Explain why a leaky air-control layer can undo good insulation

What you build

Wrap a 2×6 wall so heat slows down: fill R-19 cavities, cross every stud with R-5 foam, then keep 320 ft² under 1,700 Btu/h and the corner 2 °F above dew.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 0.048 — lab Whole-wall U at R-19 cavity plus R-5 continuous, 23 % framing
• 720 Btu/h — lab Heat flow through 320 ft² at 47 °F difference, about 211 W
• 49.5 °F — Indoor dew point at 72 °F and 45 % RH; 70 % RH reads 61.7 °F
• 62.6 °F — survive Coldest spot (corner), Doesn't hold yet inside the 2 °F gap above dew 61.7 °F

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Shell Commissioner

Envelope Command: Keep It Dry Inside

Keep It Dry Inside · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

You kept out the rain, the wind and the cold — one lesson each. Today the Shelter gets all of them at once, plus the water you cannot see, riding in the air. Grab four pens: if you have to lift one, the house leaks.

Objectives

1. Rank rain, air leaks, and vapor by how much water each can move
2. Trace each control layer around the house without lifting the pen
3. Pick a climate-matched vapor strategy and keep a drying path
4. Read the moisture index as five named penalties
5. Commission the whole shell so rain, air, heat, and humidity tests agree

What you build

Inspection day: connect water, air, heat and vapor into one skin, keep a drying path, and sign the Shelter off in rain, cold, and kitchen steam.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 0.12 — moisture-index pass line (educational comparison)
• 90% — Integrated penetrations that must be tied to all four layers
• 63.9 / 49.5 °F — lab Surface / dew point at 72 °F in, 35 °F out, 45% RH
• 0.1 perm — Class I vapor retarder ceiling (polyethylene, foil)

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Pressure Keeper

Water Command: Pressure and Flow

Pressure and Flow · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

The water tower on the horizon stores water, but its real job is pressure: every foot of height is worth 0.433 psi. Between it and the shower upstairs, gravity, friction, and sixteen elbows are taking their share. Find out where the pressure goes, then size a pipe that still has 20 psi when it arrives.

Objectives

1. Treat street pressure as a budget spent on lifting, rubbing, and turning
2. Compute velocity with 0.408 times gpm divided by d squared, and keep copper under 8 ft/s
3. Predict how diameter to the 4.87 power changes friction loss
4. Keep residual pressure at or above 20 psi at the farthest fixture under flow
5. Place a main shutoff and a fixture stop so one repair does not drain the house

What you build

Size a cold-water run from the meter to a third-floor shower. Keep 20 psi at the far fixture, hold velocity under 8 ft/s, and put a stop on every branch.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 0.433 psi/ft — water-column pressure; a 100 ft tower is about 43 psi
• 8 ft/s — copper cold-water velocity rule of thumb (about 5 ft/s hot)
• 20 psi — Residual pressure floor in this lab (IRC P2903.1 for showers, tubs, and tank toilets; 8 psi at lavs and sinks)
• d^4.87 — halving diameter multiplies friction loss about 29 times

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Gravity Marshal

Drain Command: Let Gravity Work

Let Gravity Work · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

Two inches of water in a U-shaped pipe is all that separates your kitchen from the sewer. Flush the wrong toilet and the seal can leave with a glug. Today you build the drain, the trap, and the breathing pipe on the roof — then break the seal on purpose.

Objectives

1. Explain why a gravity drain must fall the whole way, and name a belly
2. Use the IRC slope minimums and read Fall vs available depth against 10 in
3. Keep a 2–4 in trap seal by venting a short trap arm
4. Match Drain diameter to Fixture demand so Capacity / demand stays at Holds, then leave a cleanout
5. Read the four lab gauges and restore a siphoned, sagging, blocked branch

What you build

Two inches of water guard your kitchen from the sewer. Build the trap, the falling drain, and the roof vent, then steal the seal on purpose and watch a belly pond.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 1/4 in/ft — IRC P3005.3 minimum slope for pipe 2½ in and smaller
• 9.6 / 10 in — Fall vs available depth of a 40 ft run at 2 percent
• 2.55 ft/s — Manning velocity of a 3 in pipe at 2 percent (n = 0.013)
• 2–4 in — trap-seal depth (IRC P3201.2)

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Circuit Steward

Power Command: Complete the Circuit

Complete the Circuit · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

A toaster and a hair dryer on the same kitchen circuit add up to 25 amps on a 20-amp breaker, and the kitchen goes dark. The breaker was never protecting the toaster; it was protecting the wire inside the wall. Today you build that loop and find out what five thousandths of an amp can do.

Objectives

1. Relate watts, volts, and amperes with I = P ÷ V, and read Circuit current in the lab
2. Read Breaker ≤ wire rating (14 AWG → 15 A, 12 → 20 A, 10 → 30 A) and keep utilization at or under 80%
3. Calculate two-wire voltage drop and keep Voltage drop at or under 3%
4. Explain equipment grounding as a fault path that lets the breaker open
5. Explain why a GFCI watches for about 5 mA of missing current, separate from overcurrent

What you build

A toaster and a hair dryer on one kitchen circuit add up to 25 A. Build the loop, size the wire, and prove why the breaker, the ground, and the GFCI each do a different job.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 10.00 A — 1,200 W toaster at 120 V (lab default)
• 1.93 % — voltage drop on 60 ft of 12 AWG at 10 A
• 80 % — continuous-load target; 20 A breaker → 16 A
• 5 mA — GFCI threshold (UL 943 Class A); a 20 A breaker is 20,000 mA

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Light Shaper

Light Command: Shape the Room

Shape the Room · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

A full moon gives you 0.2 lux; noon sun, a hundred thousand; and your eyes read a book under both. A classroom needs about 400 — landing on the desk, not the ceiling. Today you decide where every lumen falls, and find out why the brightest room in the building can be the one nobody can see in.

Objectives

1. Distinguish lumens (lamp output) from lux and footcandles (light on the desk)
2. Compute Average illuminance with the lumen method on the 17.84 m² lab room
3. Use inverse square, Beam angle, and Mounting height to size a footprint
4. Keep Uniformity index at or above 0.62 so corners match the middle
5. Hold Glare index at or under 1.15 by spreading light, not stacking lumens

What you build

Hang four 2,600-lumen downlights over a 16 × 12 ft learning room, land 379 lux on the desk, and find out why two spotlights at 364 lux still fail.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 379 lux — lab Average illuminance (4 × 2600 × 0.65 ÷ 17.84 m²); Installed output 10,400 lm
• 364 lux / 0.41 / 4.17 — Stress Test Average illuminance, Uniformity index, Glare index (Installed output 10,000 lm)
• 300–750 lux · Uniformity index ≥ 0.62 · Glare index ≤ 1.15
• 1 footcandle = 10.76 lux; 60-watt-equivalent LED ≈ 800 lumens (rule of thumb)

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Air Balancer

Climate Command: Move Heat and Air

Move Heat and Air · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

Your air conditioner has never cooled a room in its life — it cools air, and a fan delivers it like a truck, a trash can of air every second. Shut the bedroom door and the truck stalls. Today you run the whole loop: load, delivery, return, filter, humidity — on a 105-degree day with eight people in the room.

Objectives

1. Compute sensible capacity as 1.08 × cfm × ΔT and compare it with Modeled load
2. Read Supply air changes (recirculated) as cfm × 60 ÷ volume, not outdoor air
3. Keep Return path Complete so supply air can leave the room
4. Separate particle filtration from ventilation that dilutes gases
5. Hold Indoor humidity between 35 and 60 percent on Humidity / filter

What you build

Shut the bedroom door and cool air stalls. Balance a 240 ft² room: 6,124 Btu/h load, 420 cfm, an open return, a filter, and humidity in the 35–60% band.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 1.08 × cfm × ΔT — sensible capacity in Btu/h (standard air)
• 6,124 Btu/h load vs 6,940 Btu/h delivered — lab default at 420 cfm with 10% Duct loss
• 11.67 /h — lab Supply air changes (recirculated) at 420 cfm × 60 ÷ 2,160 ft³; pass band 3–15
• 1 ton = 12,000 Btu/h ≈ 400 cfm (rule of thumb); indoor RH below 60%, ideally 30–50% (EPA)

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.

Two-Minute Guardian

Safe House Command: Detect, Escape, Protect

Detect, Escape, Protect · 50 min · Ages 10–14

Preview in the AcademyPreview lesson

Hook

From the first beep of the alarm, you may have two minutes. Not to stay and watch — to leave. Today you design the house that makes those two minutes longer, the path that makes them shorter, and the plan your family will actually use at 3 a.m.

Objectives

1. Place interconnected smoke alarms so Detector coverage ratio stays at or under 1.00
2. Give every sleeping room two ways out, including a 5.7 ft² escape opening
3. Keep the required exit 32 in clear and hallways 36 in, openable without a key
4. Use Compartmentation Protected to grow Available safe time by 35 percent
5. Compare Evacuation time with Available safe time and keep Paths and guidance at Redundant + lit

What you build

From the first beep you may have two minutes. Cover 900 ft² per alarm, keep two ways out and a 32-in door, close the rated partition, and beat the smoke clock.

Nine stages

1. Read & ListenBriefing7 chapters

   Play Atlas, or read each chapter, then say the objective under it in your own words before you press Next.

2. Watch It WorkThe Raise6 operations

   After each step, drag the model round and find the new piece. Ask what would happen if it were missing.

3. Knowledge GateProve It6 questions

   If an answer is wrong, the model explains why. Read the reason, look back at the model, then try again.

4. Guided BuildAssemble6 build steps

   Think about what has to exist before the next piece can be placed. The order is the lesson.

5. Numbers LabCount Itcomputed model

   Move one control at a time and watch which gauge moves. Read the formula line: it shows the arithmetic, not a stored answer.

6. InspectorChallenge4 inspector cases

   Look at the model before choosing. Something is missing, undersized, or out of order.

7. Stress TestSurvive Itstarts failing

   Find the gauge that reads Doesn't hold yet first. Change the control that feeds it, and read what else moves.

8. Your DesignInventyour design

   Start from something that works, then make it bigger, lighter, or bolder and see what breaks first.

9. Public MissionServeone mission

   Do it with a grown-up. The safety line is part of the mission, not a footnote.

Key numbers

Educational figures from the numbers lab, not engineering guidance.

• 2 min — NFPA public message: time you may have after the alarm in a modern home fire
• 900 ft² — coverage of one spot-type smoke alarm (NFPA 72, 30 ft spacing)
• 32 in — Clear exit width pass line in this lab (IRC R311.2 required egress door); hallway 36 in
• 5.7 ft² — net clear of a bedroom escape opening; 20 × 24 in is only 3.3 ft²; sill ≤ 44 in (IRC R310)

This is a preview. The chapters, build steps, inspector cases, labs, and the Serve mission open with the household plan. See plans.