← Back to course
Matter Lab 6-8 / Week 12 / Wednesday
3/6
Week 12 · Design at the Bench

Wednesday

Bench Lab: Build and test
// Criteria, constraints, build, test, improve, report
⏱ about 20 min

Wednesday: Bench Lab: Build and Test

A grown-up pours warm tap water into two cups while Rocket holds the thermometer. "Both at 41 degrees," he says. "Start."

His cup wears a paper towel wrap, a foil layer and a second cup outside that. The plain cup stands alone.

Raven sets a timer. "Five minutes. Nobody touches either cup."

Nova hovers between them. "While you wait," she says, "write what you expect. A prediction before the number is worth more."

At five minutes Rocket reads both. "Plain cup 36. My cup 38." At ten: "Plain 33. Mine 36."

"Three degrees better," Raven says. "What do you notice? It worked, but the gap is small. What would you change?"

"Air gap," Rocket says. "Tomorrow I leave space between the cups."

Build to your plan

Build the prototype you sketched on Monday. Stay inside your constraints. If a material is not on the Bench, it is not in the design.

Then run the fair test you planned yesterday. Measure amount, time and temperature, and write every number down as you go.

A prototype that misses its criterion is not a failure. It is the first data point. The standard says a solution is tested, then modified based on the results.

  • Insulated cup: two or three cups, paper towels, foil, a zip bag, tape, a kitchen thermometer. A grown-up pours the warm tap water.
  • Cold pack: a zip bag, one quarter cup of vinegar or lemon juice, baking soda, measuring spoons, a kitchen thermometer, a towel
  • Fizzing boat: a small open cup or lid that floats, a large pan of water, vinegar, baking soda, a ruler, a timer
  • For every device: the Bench Log, your data table and a pencil
Safety first
Wear safety glasses or sunglasses for the cold pack and the boat. Fizz can splash.
A grown-up pours the warm water. Nothing hotter than warm tap water is used.
Never seal a fizzing mixture. The zip bag stays open at the top. The boat stays open. Gas must escape.
Nothing is tasted or smelled up close. Keep your face back from the fizz.
Only vinegar, lemon juice, baking soda and water go in the devices. Never cleaners of any kind.
Pour leftovers down the sink with running water. Wash hands when done.
  1. Set up the control and the prototype side by side. Check that the amounts match exactly.
  2. Record the starting temperature of both, or the starting position of the boat, at time zero.
  3. Start the timer. Cup: read both thermometers at five and ten minutes. Pack: add the baking soda and read every 30 seconds until the lowest number. Boat: add the baking soda and time how long it moves.
  4. Record every reading in your data table the moment you take it.
  5. Measure the result: degrees dropped, lowest temperature reached, or distance traveled with the ruler.
  6. Compare the prototype to the control. Did you meet your criterion? Write yes or no and the numbers.
  7. Write one change for tomorrow. Change only one thing.
TestAmount usedTimeTemperature or distanceMet the criterion?
Control
Prototype 1
READING YOUR TEST
  • Read the question.
  • Tap your answer.
In the story, the plain cup dropped 8 degrees and Rocket's cup dropped 5. Did his cup meet his criterion?
Your cold pack reading drops from 20 to 16. What happened to the heat?
Why record each reading the moment you take it?
TEST DAY IN ORDER
  • Tap a card.
  • Then tap its spot.
1First
2Second
3Third
4Fourth
Lab checkTrue or false?
A prototype that misses its criterion gives useful data.?
The zip bag for the cold pack should be sealed shut.?
The control and prototype use the same amounts.?
You should change several things at once for tomorrow.?
WHY THIS EXERCISESafe, fair tests make the numbers in your report trustworthy.
For a grown-up
A grown-up pours the warm tap water and stays close during the fizzing tests. Safety glasses or sunglasses for anything that fizzes.
Expect some mess. A towel under the whole Bench and a pan under the boat keep it simple.
If a device does not work, that is part of the lesson. Tomorrow is for improving it.
Try it
Before cleanup, look at your prototype and name its weakest spot. Is heat leaking at the top? Does the boat tip? Is the fizz too slow?
Write the weak spot and one fix in the Bench Log. That fix is tomorrow's single change.
Draw your prototype as you built it, with every layer or part labeled. Mark with an arrow where you think the most heat, cold or fizz escaped.

Real data from a real build. Tomorrow you read a reference table that explains why some materials hold heat better, then improve your design.

← Tuesday