Rocket draws a slider with a pointy shape inside.
"This is the wedge!" Rocket says proudly.
Raven looks. "What do you notice? Where do the teeth go in?"
Nova glows. "Would you like a hint? Two rows, one path out."
Rocket draws two rows going in and one row coming out.
A cutaway shows the inside of a thing.
Today you draw the inside of a slider.
Show two rows going in and one locked row coming out.
You pull the slider up.
The two rows of teeth enter at an angle.
The wedge pushes the teeth together.
The bumps lock into the dips, one by one.
| Sentence | True or false? |
|---|---|
| The slider has a wedge inside. | ? |
| Fingers lock zipper teeth faster than a slider. | ? |
| The teeth have bumps and dips that fit together. | ? |
| A zipper is a machine. | ? |
Next week we open up a lock and key.
A key has a secret shape that fits the lock.
Ask a grown-up for an old padlock with its key.
You explained a machine like an engineer. Wonderful!
Tomorrow is Machine Day with your family.