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Everyday Machines / Week 03 / Wednesday
3/6
Week 03 · Lock and Key

Wednesday

Look closely at a padlock
// A key's shape lifts the pins just right
⏱ about 15 min

Wednesday: Look Closely at a Padlock

Rocket brings a padlock with its key. "A grown-up said yes!"

Raven turns the key slowly. Click. The loop pops open.

"What do you notice? The key turned just a little," Raven says.

Nova glows the keyhole. "Would you like a hint? Look at its shape."

You need

  • A padlock with its own key
  • Two or three other keys to compare
  • A grown-up to approve and help
Safety first
Only use a padlock a grown-up approves, with its key.
Never lock anything onto a person or a pet.
Keep fingers out of the loop when it closes.
Keys and small locks stay away from younger siblings.

Padlock tour

  1. Look at the keyhole. What shape is it?
  2. Look at the key's edge. Count the bumps.
  3. Slide the key in. A grown-up turns it.
  4. Watch the loop pop open.
  5. Close the loop. Try the key again.
  6. Lay the other keys next to it. Compare the bumps.
WHAT DID YOU SEE?
  • Read the question.
  • Tap your answer.
What shape is the keyhole?
What happens when the right key turns?
Who turns the key in the padlock?
KeyHow many bumps?Tall or short bumps?
Padlock key
Key 2
Key 3
For a grown-up
Hold the padlock steady while your child looks.
Ask: which key has the most bumps?
Keep the padlock key in your hand between tries.
SentenceTrue or false?
The keyhole is a thin slot.?
You may lock the padlock onto a pet.?
Different keys have different bump patterns.?
WHY THIS EXERCISELooking closely shows why only one key fits.
Try it
Hold the padlock key and another key side by side.
Line up the bumpy edges.
Where are they the same? Where are they different?
KEY DETECTIVE
  • Read the question.
  • Tap your answer.
Two keys have different bumps. Do they open the same lock?
Which part of the key does the work inside?
Draw the padlock key and one other key. Show the bumps.

You looked closely like a real engineer!

Tomorrow we test the padlock with different keys.

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