A Wonderleaf question
How does a zipper hold together?
a real page from the book
A zipper holds because each side has shaped teeth that fit into the teeth on the other side. When you pull the slider up, it pushes the two rows together so the teeth interlock in a long, flexible chain.
The slider is doing the careful guiding. One direction squeezes the teeth into place; the other direction separates them again. Each tiny connection is small, but a whole row of them can keep a coat, bag, or tent flap closed.
Wonder words
- zipper
- slider
- teeth
- interlock
Try it out
Zip a jacket slowly while watching one tooth at a time, then unzip it and notice where the rows separate.
Read the whole picture book
Watercolour scenes, straight answers, about three minutes cover to cover.
Open the picture bookKeep wondering
- How does a vacuum cleaner pick up dirt?
- How do airplanes fly?
- How are books made?
- How do electric cars work?
- How do refrigerators keep food from spoiling?
And the next question?
Ask anything — Wonderleaf writes and illustrates a picture book for it. That's the whole idea.
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