Day 3 :: June 10
Welcome to Day 3 — your final day.
Today: show off your tie-dye shirts, take a group photo, build a paper circuit that warns you when something goes wrong, make ice cream from scratch using chemistry, and share your best work from the week.
Last 4 Corners of the week. Walk to the corner that matches your answer. 30 seconds to talk in each corner.
- Corner A — Sweet corn from a roadside stand.
- Corner B — A scoop of Blue Bunny from Le Mars.
- Corner C — Funnel cake or a fresh pork tenderloin at the county fair.
- Corner D — Watermelon at a backyard BBQ.
- Corner A — How something I built actually worked.
- Corner B — How fast a project failed and how I had to rebuild.
- Corner C — Something a teammate did that I didn't expect.
- Corner D — A piece of science I didn't know before.
- Corner A — Frustrated — I wanted it to work.
- Corner B — Curious — I want to know why it failed.
- Corner C — Done — I move on to something else.
- Corner D — Determined — I'll fix it no matter how long it takes.
You folded, bound, dyed, took home, and rinsed. Today is the payoff — everyone wears their tie-dye, we look at the science behind what happened, and we get the official group photo of the week.
Take a few minutes to look at every shirt in the room. They all started identical — white cotton, same dye kits — but no two look the same.
- What matched what you predicted?
- What surprised you about the final result?
Three things made every shirt unique:
- The fold — spiral, accordion, or crumple created the pattern grid.
- The rubber bands — wherever they squeezed the fabric, dye couldn't reach. Those became your white lines.
- The chemistry — Tulip dye is a fiber-reactive dye. The molecules formed permanent chemical bonds with the cotton fibers when the dye sat overnight. That's why it doesn't wash out.
This is the same chemistry you saw in chromatography on Day 1 — dye molecules moving through fibers and stopping at different points based on size, weight, and barriers. You used both demonstrations to predict your shirt result.
Everyone together. Bring your shirt — even if you're not wearing it, hold it up.
Big group shot first, then table-by-table shots, then any silly poses your facilitator green-lights. This photo is going up on the Briar Cliff TS wall.
Every airplane cockpit, every nuclear plant, every hospital monitor has warning lights. Engineers call them fail-safe indicators. When the light is off, things are fine. When it's on, something is wrong. The light has to be honest — it must turn on every time the bad thing happens, and never falsely. Lives depend on it.
Today you build one.
The light turns ON when a flap or panel that should stay shut is opened. Real-world version: a refrigerator door alarm, a medication cabinet alert.
The light turns ON when something is placed on a small paper square. Real-world version: a doorstep sensor, a weight detector.
The light turns ON when a structure tilts past a safe angle. Real-world version: a forklift tip-over warning, an earthquake sensor.
The light turns ON when a tape seam or glue joint starts to pull apart. Real-world version: a bridge crack monitor, an aircraft stress sensor.
- Cardstock
- 1 coin battery (CR2032)
- 1 LED
- Copper tape (¼ inch)
- Scissors
- Pencil
- Small folded paper pieces for spacers and switches
Watch this first — it shows how copper tape and coin batteries make a basic LED circuit.
Step A — Build the base circuit: Lay copper tape on cardstock to form a complete loop with one gap at your switch point. Tape the LED across the gap — longer leg on the positive side. Tape the battery positive-side down onto the positive line.
Step B — Build your switch:
- Scenario A: Cut a hinged flap in the cardstock. Put copper tape on the inside of the flap and on the matching spot on the base. Place a thin paper spacer between them. When the flap lifts, the spacer drops away and the copper strips touch.
- Scenario B: Stack two pieces of cardstock with copper tape facing inward. Place a small paper ring spacer between them. At rest the tapes don't touch. When weight presses down, they connect.
- Scenario C: Tape a paperclip inside a folded paper channel. At rest it sits away from the circuit. When tilted, it slides down and bridges two copper tape lines.
- Scenario D: Build a paper joint held by tape. Run copper tape strips on both halves, held apart by a folded paper bridge. When the joint pulls apart, the bridge collapses and the strips touch.
Trigger your failure condition 10 times. Count how many times the light turns on correctly.
- Successes (light on when condition fails): __ / 10
- False alarms (light on when condition is safe): __ / 10
A truly honest light scores 10/10 with zero false alarms. If yours isn't there yet — find where the copper tape is touching when it shouldn't, add a thicker spacer, and test again.
Reliability engineers at NASA, Boeing, and every hospital design warning systems that must never lie. They study every possible way a system could fail and make sure there's a light for each one. Honest warning lights save lives when people listen to them.
Adding salt to ice lowers its freezing point — the ice melts below 0°C, creating a super-cold slushy mixture that pulls heat out of your cream mixture fast enough to freeze it. This is called freezing point depression. It's the same chemistry that keeps roads ice-free in winter.
Bonus connection: the world's largest ice cream factory is Blue Bunny in Le Mars, Iowa — about 30 minutes from here. They use giant industrial versions of the same chemistry you're about to use in a sandwich bag.
- What is the job of the salt?
- What do you think happens if you leave the salt out entirely?
- Why does the outer bag feel colder than the inner bag?
- ½ cup half-and-half
- 1 tablespoon sugar
- ¼ teaspoon vanilla extract
- ½ cup salt
- Ice cubes
- 1 quart-sized zip bag
- 1 gallon-sized zip bag
- Spoon
- Pour the half-and-half, sugar, and vanilla into the quart bag. Squeeze out as much air as you can and seal it tight. Double-check the seal — salt water getting in ruins the ice cream.
- Fill the gallon bag about halfway with ice. Add the salt directly to the ice.
- Place the sealed quart bag inside the gallon bag. Squeeze out excess air and seal the outer bag.
- Shake, squish, and massage the bag constantly for 5–10 minutes. The cream mixture should thicken and freeze into soft-serve.
- When it feels like soft-serve, carefully remove the quart bag. Rinse the outside under cold water to remove salt before opening.
- Open, grab a spoon, and eat.
While you eat, discuss with your team:
- Did your prediction about the salt match what actually happened?
- What do you think would happen if you used twice as much salt?
- Where else have you seen freezing point depression in real life?
Three days of building, testing, failing, and improving. Time to share.
As a team, pick one or two projects from the week to share. It doesn't have to be your most successful one — pick the one that taught you the most, surprised you the most, or that you're most proud of.
You have a few minutes to decide what you'll say.
- What did you make or do?
- What failed — and what did you do about it?
- What's one thing you'd change if you did it again?
Bring any artifacts you have — your handout, your robotic arm, your Water Park Mystery data, your honest light.
While other teams share, listen for:
- A failure that turned into a solution
- A design choice you wouldn't have thought of
- Something you'd steal for your own build next time