Grades K–2 · Machines
How does a zipper join its two sides?
One little pull can close the long opening of a coat. A zipper does this with many tiny parts working together. Along each cloth edge is a row of teeth. Their shapes fit together, a little like pieces of a puzzle.
The part you pull is attached to a slider. Inside the slider is a short tunnel shaped like the letter Y. Two separate rows enter its wide end. The tunnel guides their teeth toward each other until they fit together. A joined row leaves the narrow end.
As the slider travels up the coat, it joins more teeth behind it. Those teeth hold the two cloth edges together. They stay joined even after the slider has moved past them.
Follow the two rows into the Y-shaped tunnel. The lower picture shows the same zipper after the slider has moved farther up.
Pulling the slider down reverses the journey. Its middle divider guides the joined teeth into two separate paths. The coat opens again. The zipper can join and separate the same teeth many times: a carefully shaped moving part turns one pull into a whole row of little joins.
About this explanation
The teeth and tunnel are enlarged so their shapes are easier to see. Real zipper teeth have several different designs.
Starting knowledge: Recognize joined and separate pieces and describe movement up and down.
Sources
- YKK — The structure of a zipper