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Everyday Machines / Week 04 / Thursday
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Week 04 · The Faucet

Thursday

Test the washer material
// A twist that stops the water
⏱ about 15 min

Thursday: Test the Washer Material

"Why is the washer rubber?" Rocket asks. "Why not paper?"

Raven lines up a rubber band, a paper strip, a paper clip.

"What do you notice when you stretch each one?" she asks.

Nova blinks. "Test them one at a time."

Why the material matters

A washer must squish a little and spring back.

Rubber is the main stretchy material found in nature.

Stretch rubber and let go. It goes back to its size.

Paper tears. Metal bends and stays bent.

So a soft rubber washer fits the job.

  • A rubber band
  • A strip of paper
  • A metal paper clip
  • A cup of water and a tray
  • Paper and a pencil
Safety first
Do the water test over a tray or the sink.
Nothing goes in your mouth.
Rubber bands and paper clips stay away from little kids.
A grown-up unbends the paper clip for you.

Test one: stretch and let go

  1. Pull the rubber band gently. Let go. What happens?
  2. Pull the paper strip gently. What happens?
  3. Bend the paper clip. Let go. What happens?
  4. Write what you saw in the table.
MaterialDid it go back to its shape?
Rubber band
Paper strip
Paper clip

Test two: the drip count

  1. Turn the cold faucet on, then all the way off.
  2. Watch the spout for one minute.
  3. Count every drip you see.
  4. Write the number in your table.
FaucetDrips in one minute
Kitchen
Bathroom
WHAT HAPPENED?
  • Read the question.
  • Tap your answer.
Which material went back to its shape?
Why is a faucet washer made of rubber?
A faucet drips when it is off. What might be worn?
SentenceTrue or false?
Rubber stretches and goes back to its size.?
Paper is a good washer material.?
A fair test changes one thing at a time.?
WHY THIS EXERCISEDifferent materials fit different jobs. Rubber fits the washer job.
FAIR TEST CHECK
  • Read the question.
  • Tap your answer.
You test three materials. How many do you stretch at a time?
Which material tore?
Draw the three materials. Circle the one that sprang back.

You tested materials like an engineer!

Tomorrow, you explain the whole faucet.

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