A Wonderleaf question
How does a zipper hold together?
a real page from the book
A zipper holds together because each side has shaped teeth that interlock when the slider guides them into line. As you pull the tab, the slider narrows the two rows toward each other, so bumps and hollows meet in order and form one flexible chain.
The neat detail is that the pull does not fasten every tooth at once. It lines up one tiny connection after another, like closing a gate made of many small hooks. Reverse the same slider, and those connections are guided apart without breaking the teeth.
Wonder words
- slider
- teeth
- interlock
- wedge
Try it out
Zip a coat slowly while looking at the teeth, then unzip it and notice how the same pull separates the rows.
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?
One more wonder: Why is space so dark?
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