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Everyday Machines / Week 02 / Wednesday
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Week 02 · The Zipper

Wednesday

Look closely at a zipper
// Rows of hooks and a slider that is a wedge
⏱ about 15 min

Wednesday: Look Closely at a Zipper

Rocket brings an old bag with a big zipper.

"A grown-up said we can use this one!" Rocket says.

Raven looks at the teeth up close.

"What do you notice? Every tooth looks the same," Raven says.

Nova zooms in with a glowing circle.

"Would you like a hint? Find the bump on each one."

You need

  • An old bag or coat with a zipper
  • A magnifying glass, if you have one
  • A grown-up to approve the zipper
Safety first
Only use a zipper a grown-up approves.
Never cut a zipper or pull teeth off.
A grown-up handles anything sharp.
Zip slowly so the slider does not pinch skin.

Zipper tour

  1. Open the zipper all the way.
  2. Look at one row of teeth. Find a bump on a tooth.
  3. Look at the other row. Find the gaps between teeth.
  4. Zip it halfway. Look at the locked teeth.
  5. Look at the slider from the top. Find the pointy shape.
WHAT DID YOU SEE?
  • Read the question.
  • Tap your answer.
What is on each tooth?
Where do the bumps fit?
Who approves the zipper you use?
What I looked atWhat I saw
One tooth
The locked teeth
The slider from the top
For a grown-up
Help your child find the bump and dip on a tooth.
Ask: do all the teeth look alike?
Point out where the two rows enter the slider.
SentenceTrue or false?
Every tooth on a zipper looks about the same.?
It is fine to cut a zipper to see inside.?
The two rows meet inside the slider.?
WHY THIS EXERCISEMatching parts are what make the rows lock.
Try it
Zip the zipper closed.
Gently try to pull the two sides apart with your hands.
Do the teeth let go? Now use the slider.
TIGHT TEETH
  • Read the question.
  • Tap your answer.
Locked teeth are pulled gently sideways. What happens?
What opens the teeth easily?
Draw three teeth locked together. Show the bumps.

You looked closely like a real engineer!

Tomorrow we test the slider against our fingers.

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