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Builder's Lab / Week 01 / Tuesday
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Week 01 · Think Like an Engineer

Tuesday

A fair test
// Ask, imagine, plan, create, test, improve
⏱ about 20 min

Tuesday: A Fair Test

Rocket and Raven race two paper cups down a slide of cardboard.

Rocket pushes one cup hard. Raven just lets the other cup go.

"Mine is faster!" Rocket cheers.

Raven tilts her head. "What do you notice? You pushed yours."

Nova blinks. "Interesting. Was that race fair?"

Change one thing

A fair test changes only one thing.

Everything else stays the same.

Then you know what made the difference.

Rocket's race

Rocket pushed one cup. Raven did not push hers.

So the push was different, not just the cup.

That race was not fair.

Fair test rule
Change one thing.
Keep the rest the same.
Test it the same way each time.
FAIR OR NOT FAIR?
  • Read the question.
  • Tap your answer.
Two cups start at the same spot. Nobody pushes. Is it fair?
One cup starts higher on the slide. Is it fair?
IdeaTrue or false?
A fair test changes only one thing.?
A fair test changes everything at once.?
In a fair test, you test the same way each time.?
WHY THIS EXERCISEWhen one thing changes, you know it made the difference.
RAVEN'S NEW RACE
  • Read the question.
  • Tap your answer.
Raven wants to test a big cup and a small cup. What should stay the same?
For a grown-up
Try a quick fair race with two cups.
Lean a big book on a few books to make a ramp.
Let both cups go from the same line with no push.
Safety first
Keep the ramp low and steady.
Keep cups away from faces.

Raven plans a fair test

Raven wants to know something.

Does a big cup or a small cup roll farther?

She uses the same ramp for both cups.

She lets both cups go from the same line.

Only the cup size changes.

KEEP IT FAIR
  • Read the question.
  • Tap your answer.
Rocket tests a steep ramp and a low ramp. What changes?
In that test, what should stay the same?
Raven pushes one cup and not the other. Is it fair?
Why do engineers like fair tests?
RUN A FAIR TEST
  • Tap a card.
  • Then tap its spot.
1First
2Next
3Then
4Last
Try it
Set up the book ramp again.
Pick one thing to change.
Keep the rest the same.
Race the cups two times and watch.
Safety first
Keep the ramp low.
Roll cups away from people and pets.
RaceFair test?
Same cup, same start, two ramps.?
New cup, new start, new ramp.?
Same ramp, same start, two cup sizes.?
WHY THIS EXERCISEA fair test changes just one thing.

You know the fair test rule now!

Tomorrow, we build our first cup tower.

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