This week, you build. Today you build a bridge out of dry spaghetti that crosses a 14-inch gap between two desks and holds as many marbles as you can load on it.
No glue. Just spaghetti, tape, and string. Sketch it, build it, test it until it breaks, and write down your number. Tomorrow the gap gets bigger.
🌉 Spark: Why Bridges Don't Fall~10 min
Every bridge on Earth is fighting two forces at once:
Compression — a squeezing, pushing force. Think of stepping on a soda can.
Tension — a pulling, stretching force. Think of a tug-of-war rope.
Spaghetti has a split personality
Push straight down the length of a strand and it's surprisingly strong — that's compression. But bend it or pull a taped joint apart and it snaps instantly. Your whole job today is to arrange the spaghetti so the weight pushes along the strands, and use the string for anything that needs to be pulled.
Talk it out
One strand of spaghetti is about 10 inches. Your gap is 14 inches. So a single strand can't even reach across. With your partner: how will you join strands to make it span? Bundle them together? Overlap and tape? Build triangles?
🛠️ The Build Challenge~45 min
Your mission: Build a spaghetti bridge that
spans the 14-inch gap and rests on both desks,
holds a cup hung from its center,
and carries as many marbles as possible before it fails.
Materials per team & rules
50 strands of spaghetti, 1 roll of masking tape, 1 piece of string (1 m).
Use only what you're given.
You may tape the ends down to the desktops — those are your abutments (the supports real bridges sit on).
The cup hangs from the center of the span.
Instructions
Part I: Sketch it first (~8 min)
Before you tape anything, draw your bridge on paper. Mark:
where strands bundle together to make a thick beam,
where you'll add triangles for strength,
where the string goes,
where the cup will hang.
Instructions
Part II: Build (~37 min)
Bundle for strength. One strand bends and snaps. Tape 3–4 strands together into a thick beam and it gets dramatically stronger.
Triangles beat squares. A square folds flat under load; a triangle can't. Brace your bridge with diagonal strands.
Tape joints with overlap. Where two pieces meet, overlap them and wrap the tape. Loose joints are where bridges fall apart.
Use the string for pulling. String is strong when stretched and useless when pushed. Run it underneath, desk to desk, as a tension line to help hold the load up.
Reinforce the center. That's where the cup hangs and the force piles up. Make it your strongest point.
Heads up: spaghetti ends are pointy — don't poke. Snapped pieces and stray marbles roll; keep the floor clear.
⚖️ Load Test: Marbles to Failure~15 min
There are 4 test cups in the room. When one is free, bring it to your gap — you don't have to wait for everyone. As soon as your bridge is done, test it.
Hang the cup from the center of your bridge using the paper-clip hook.
Add marbles a few at a time. Keep going until the bridge breaks or the cup touches down.
Count the marbles it held the moment before it failed. That is your score.
Pour the marbles back into the bin for the next team.
Write it down: 📋 My number = marbles held + the part that broke first.
Finished early? Beat your own number
Rebuild the part that failed and test again. Or go for efficiency: can you hold the same marbles using fewer strands? Tomorrow, efficiency becomes the whole game.
💭 Wrap~10 min
Finish these on your paper:
My bridge held ___ marbles across 14 inches.
The first part to fail was…
If I built it again, the one thing I'd change is…
Career Connection
Structural and civil engineers do exactly what you just did: arrange material so forces travel through it as push (compression) and pull (tension). And they test bridges to failure on purpose — the only way to know how strong something really is.
Week 3 · 80 minutes
DAY 2
Redesign: The 20-Inch Span
Yesterday the gap was 14 inches. Today it's 20. That's longer than two strands of spaghetti laid end to end. A simple flat beam will sag in the middle and snap.
Today you redesign. The winning teams won't use more spaghetti — they'll use it smarter.
📐 Spark: Why 20 Inches Changes Everything~10 min
The longer a beam spans, the more it bends in the middle — and bending is exactly what spaghetti is worst at. Double your gap and a flat beam is hopeless.
So engineers invented the truss: a frame made of triangles. A truss turns bending into pure push and pull — which is perfect, because that's exactly what your two materials are each good at.
The truss rule
The top of a truss gets squeezed → compression → use bundled spaghetti.
The bottom of a truss gets stretched → tension → use the string.
The diagonals between them make the triangles that hold it all together.
New scoring today: efficiency
Your score is marbles held ÷ spaghetti strands used. Holding 80 marbles on 40 strands beats holding 90 marbles on all 50. The lesson: smart, not heavy. Every strand you don't use makes your score go up.
🛠️ The Redesign Challenge~45 min
Your mission: Build a bridge that spans the 20-inch gap and holds the most marbles — with the best efficiency (marbles ÷ strands used). Two champions today: most marbles and most efficient.
Materials per team
50 strands of spaghetti, 1 roll of masking tape, 1 piece of string (1 m). Same as yesterday — but today, count how many strands you actually use.
Instructions
Part I: Redesign sketch (~8 min)
Plan a truss on paper. Label:
the top chord (compression → spaghetti bundles),
the bottom chord (tension → string),
the diagonals that turn it into a row of triangles,
your strand budget — how many of the 50 you plan to use.
Instructions
Part II: Build the truss (~37 min)
String the bottom chord first. Pull the string tight from desk to desk underneath. This is your tension line — it carries the pull.
Build the top chord from bundled spaghetti. Tape 3–4 strands together so it can take the squeeze without bending.
Connect top to bottom with diagonals to make a row of triangles. Triangles are what let a truss cross a long gap.
Spend strands carefully. Don't dump all 50 in. Every strand you leave out raises your efficiency score.
Test the empty span first. Does your bridge hold its own shape across 20 inches before any marbles go on? If it already sags, fix it now.
Heads up: pointy spaghetti ends, and marbles roll. Keep the floor clear.
⚖️ Load Test + Efficiency~15 min
Same 4 test cups, same rule: when one is free, bring it to your 20-inch gap and test.
Hang the cup from the center with the paper-clip hook.
Add marbles a few at a time until the bridge fails.
Count the marbles it held. Then count the strands you used.
Pour the marbles back into the bin.
Do the math
Efficiency = marbles held ÷ strands used. Example: 60 marbles on 30 strands = 2.0. 80 marbles on 50 strands = 1.6. The first bridge wins on efficiency even though it held fewer marbles.
Write it down: 📋 My numbers = marbles held, strands used, and efficiency.
💭 Wrap~10 min
Did you hold more marbles over a longer gap than yesterday? Why do you think that is?
Finish the sentence: spaghetti is strong in ______ and weak in ______. String is the opposite.
Whose bridge was the most efficient in the room? What did they do differently?
Career Connection
Look closely at any real bridge or crane and you'll see triangles everywhere. That's not decoration — it's the cheapest way to make material span a gap. Structural engineers get paid to hold the most load with the least material. That's the exact game you just played.
Next: we trade spaghetti for circuits. Wednesday we head to the computer lab and turn foil into a keyboard with Makey Makey.
Week 3 · 80 minutes · Computer Lab
DAY 3
Makey Makey: Turn Anything Into a Key
📺 Type these on your computer
First demo (drums)
makeymakey.com/Bongos
Conductivity test
apps.makeymakey.com/play
then tap Is It Conductive?
Instrument (piano)
apps.makeymakey.com/piano
Controller games
arcade.makeymakey.com/play
then tap Space Rocks or Runner
New tools, same builder mindset. A Makey Makey makes your computer think a banana — or a square of foil, or your own hand — is a keyboard key.
Over the next three days you'll build either a musical instrument or a game controller out of foil and cardboard, and on Friday everyone plays everyone's. Today: get it working, find out what's conductive, and pick your project.
⚡ Spark: How It Works~8 min
A Makey Makey is a little board that pretends to be a keyboard and mouse. Plug it into the computer with the USB cable. There's nothing to install.
The one big idea: you complete the circuit
A key "presses" only when electricity makes a full loop: out of the board → through a wire → through something conductive (foil, a paper clip, your body) → and back to the board's EARTH. You are part of the loop. Hold EARTH in one hand, touch a foil pad with the other, and the circuit closes — the key fires.
🔌 Plug In & Explore~30 min
Where the keys are on the board
Front (use the alligator clips): the 4 arrows, SPACE, CLICK, and the EARTH bar along the bottom.
Back (use the jumper wires): W, A, S, D, F, G — extra keys for when you need more than the front ones.
Instructions
Part I: Get one key working (~15 min)
Plug the Makey Makey into the computer with the USB cable. A light comes on.
Clip one alligator clip to EARTH (the metal strip along the bottom front).
Clip a second alligator clip to SPACE, and clip its other end to a piece of foil.
Hold the metal end of the EARTH clip in one hand. With the other hand, touch the foil.
Open makeymakey.com/Bongos and touch the foil — it should play a drum every time.
Nothing happens? Check: are you holding EARTH? Is every clip biting bare metal, not plastic?
Instructions
Part II: What closes the circuit? (~15 min)
Open apps.makeymakey.com/play and tap "Is It Conductive?" Clip the test wire to each item and touch it (while holding EARTH). Predict first, then test.
Test from your kit: foil, a paper clip, a brad, the cardboard, the foam slice, the hair tie, your own skin, a pencil scribble.
Why it matters: the conductors (foil, metal clips, brads, your body) can become keys. The non-conductors (the hair tie, dry cardboard) are just structure. That tells you which kit parts do which job.
🎯 Pick Your Project & Sketch~30 min
With your partner, choose ONE to build this week:
🎹 Option A — Instrument: a foil piano
Foil pads become piano keys, wired to the board and played at apps.makeymakey.com/piano. Add more notes using the back keys (W A S D F G).
🕹️ Option B — Controller: play a real arcade game
Build foil control pads, then play at arcade.makeymakey.com/play:
Space Rocks — arrows to fly, SPACE to fire (a full 5-pad controller).
Runner — one big button to jump (the simplest controller).
Instructions
Sketch your layout
On paper, draw where each foil pad goes and label it with the key it presses (arrow / SPACE / a letter). Then plan your ground:
Hands-free trick: clip a foil strip to EARTH and hold it against your wrist with the hair tie. Now both hands are free to play.
Time left? Start cutting cardboard and foil pads. Tomorrow is the full build.
💭 Wrap~10 min
Show your sketch to another pair. Say out loud which key each pad will press. Then check yourself:
Name two things from your kit that are conductive, and one that isn't.
In one sentence: what has to happen for a key to "press"?
Career Connection
Interaction designers and hardware prototypers invent new ways for people to control machines — touchscreens, game controllers, accessible switches for people who can't use a normal keyboard. You're doing the first version of that job right now.
Tomorrow: build it for real — cut, foil, wire, and test until your instrument or controller actually plays.
Week 3 · 80 minutes · Computer Lab
DAY 4
Build Your Invention
📺 Type these on your computer
Instrument (piano)
apps.makeymakey.com/piano
Controller games
arcade.makeymakey.com/play
then tap Space Rocks or Runner
Today you make it real. Cut, foil, wire, and test until your instrument or controller actually plays.
Most builds won't work on the first try — that's the same build, test, fix loop you ran on the bridges. Tomorrow is the showcase, so today's goal is a working build.
⚡ Recap: The Loop~5 min
A key fires when the circuit makes a full loop: board → wire → conductor → you → EARTH. Today you build the foil pads, wire them to keys, set up your ground, and debug until every key works.
🧱 Build the Contacts~30 min
Cut a cardboard base. This holds everything in place.
Cut your foil pads — one per key. (Use the 2 pre-cut foil sheets, or cut your own from the foil.)
Attach each pad to the cardboard. Three easy ways from your kit, each of which also gives the alligator clip something metal to bite:
poke a brad through the foil into the cardboard,
clip the edge with a mini binder clip,
or pin it with a large paper clip.
Build a press-button (great for "fire" or "jump")
Make a foil–foam–foil sandwich: two foil pads with the ~1 cm foam slice between them and a hole punched in the middle of the foam. Press the top → the two foils touch through the hole → the key fires. Clip one foil to EARTH and the other to your key.
🔗 Wire It + Set Your Ground~20 min
Front of the board, with alligator clips: arrows, SPACE, CLICK, EARTH.
Back of the board, with the jumper wires: W A S D F G — use these if you need more keys than the front has (like a 6-note piano).
Clip each pad to its key. Always bite bare metal (foil, brad, or clip) — never the cardboard.
Ground yourself hands-free
Clip a foil strip to EARTH and hold it against your wrist with the hair tie. Now you're always grounded and both hands are free to play.
🧪 Test + Fix~20 min
Open your app and play. Then fix what's broken.
Dead key? Walk the loop
Is the clip tight on bare metal?
Are you holding EARTH (or wearing the foil wrist strap)?
Are two pads touching each other? That shorts them — spread them apart.
Is the foil torn or the clip on a fold? Re-seat it.
Iterate: change one thing, test again. Goal: every key working, with 3 clean plays in a row.
When it works: 📋 Label your keys with the index cards so anyone can play it.
💭 Wrap~5 min
Leave your build labeled and ready for tomorrow's showcase. Write one line: which key was hardest to get working, and what fixed it?
Career Connection
Tracking down why one wire out of twenty doesn't work is the daily job of electronics and hardware technicians. They call it "walking the circuit" — exactly what you just did.
Tomorrow: finish, set up your station, and play every other team's invention.
Week 3 · 80 minutes · Computer Lab
DAY 5
Finish + Showcase
📺 Type these on your computer
Instrument (piano)
apps.makeymakey.com/piano
Controller games
arcade.makeymakey.com/play
then tap Space Rocks or Runner
Last day. Finish your build, set up your station, then everyone plays everyone's.
You'll try every other team's instrument and controller and give each one two things that worked and one to improve.
🔧 Final Fixes + Label~25 min
Fix any dead keys. Walk the loop: clip on bare metal? grounded? pads touching each other? foil torn?
Label every key with the index cards — which note, or which arrow.
Three clean plays in a row = done.
🪧 Set Up Your Station~10 min
Make it so a stranger can walk up and play it without you explaining.
Leave it plugged in with the app open (or write the app name on an index card).
Make a station card: your project name, one line on how to play it, and where to hold EARTH.
🎉 Showcase: Play Everyone's~30 min
Half the room hosts at their stations while the other half walks and plays. Then swap, so everyone hosts and everyone plays.
At each station, give 2 stars + 1 wish
2 stars — two things that worked well.
1 wish — one thing that would make it better.
As you go, hunt for two things: the most creative key in the room, and the build that worked the most reliably.
💭 Wrap: The Week~10 min
This week you ran the same loop twice — once on bridges, once on circuits: design, build, test, fail, fix, show.
Finish these:
The hardest thing to get working this week was…
One thing I can do now that I couldn't on Monday:
If I had one more week, I'd build…
Career Connection
Every gadget, instrument, and game controller started as someone's messy first build that they tested and improved. You now know the whole loop — design, build, test, fix, demo. You're a builder now.
Week 3 in the books. Two bridges and a working invention. Nicely done.
Cal State LA Upward Bound · Week 3 · Built by Woven Learning & Technology
