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Builder's Lab / Week 08 / Tuesday
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Week 08 · Float It

Tuesday

Why boats float
// A foil boat that carries the most coins
⏱ about 20 min

Tuesday: Why Boats Float

Raven crumples a piece of foil into a tight ball.

Plop! The ball sinks to the bottom.

Then she shapes the same foil into a wide, flat dish.

It floats!

"Same foil!" Rocket says. Nova beeps. "Interesting. What do you notice about the shape?"

Pushing water aside

A boat in water pushes some water out of the way.

This is called displacing water.

The water pushes back up on the boat.

That push up is called buoyancy.

Wide and flat

A flat, wide shape pushes aside more water.

More water pushed aside means a bigger push up.

A tight, small ball does not push aside enough, so it sinks.

Try it
Crumple a small piece of foil into a ball. Drop it in.
Shape another piece into a dish. Set it on the water.
Which one floats?
Safety first
A grown-up stays close by any tub of water.
Wipe up spills so nobody slips.
A grown-up tears or cuts the foil. Edges can be sharp.
FLOAT CHECK
  • Read the question.
  • Tap your answer.
Which foil shape floats?
What is the push of water up on a boat?
IdeaTrue or false?
A boat pushes water out of the way.?
A wide shape pushes aside more water than a tight ball.?
The ball sank because it was made of different foil.?
WHY THIS EXERCISEShape changes how much water a boat pushes aside.

Feel the push

Press an empty plastic cup down into the water.

You can feel the water push back up.

That push is buoyancy.

BOAT SCIENCE
  • Read the question.
  • Tap your answer.
What does a boat do to the water?
What does displace mean?
Why did the foil ball sink?
Which way does buoyancy push?
BALL TO BOAT
  • Tap a card.
  • Then tap its spot.
1First
2Next
3Then
4Last
Try it
Push an empty plastic cup into a bowl of water.
Feel the water push back.
Let go. What does the cup do?
Safety first
A grown-up stays with you near water.
Wipe up spills so nobody slips.
Draw the foil ball and the foil dish in the water.

You know why boats float!

Tomorrow, we build boat version 1.

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