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Builder's Lab / Week 09 / Build Day
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Week 09 · Balloon Car

Build Day

Build Day: Balloon Car Rally
// A car pushed by balloon air
⏱ about 20 min

Build Day: Balloon Car Rally

Raven tapes a start line across the hallway.

"Every car gets the same size balloon," she says.

Rocket checks his wheels twice this time.

Nova floats down the hallway. "I will measure each car."

Ready for the balloon car rally?

  1. Air goes out the back. The car goes forward.
  2. That forward push is called thrust.
  3. Friction from rubbing wheels slows a car down.
  4. Compare many fixes. Pick the one that fits the problem.
◇ FAMILY BALLOON CAR RALLY
Each team builds or improves a balloon car.
A grown-up blows every balloon to the same size.
Line up the cars at the start line.
Let go. No pushing!
Measure how far each car rolls.
For a grown-up
Do all balloon blowing and all cutting yourself.
Keep flat and broken balloons away from children under 8.
Skip balloons if anyone has a latex allergy.
Ask: which fixes did you think about before you built?
Safety first
A grown-up blows up every balloon.
Throw away broken balloon pieces right away.
BUILD DAY CHECK
  • Read the question.
  • Tap your answer.
A car barely moves. The wheels rub. Which fix fits?
RALLY CHECK
  • Read the question.
  • Tap your answer.
One car gets a bigger balloon. Is that fair?
Which way does the balloon straw point?
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