Hey there, it's Deysi from Design Squad.

And we got a question from appledog, who wanted to know, how does an eraser work?

That's a great question, appledog.

Erasers are made out of different materials such as vinyl, plastic or rubber.

Even though they're all made out of different materials, they still work the same way.

And here's how.

The parts of the pencil that make marks on paper is made from a mineral called graphite.

When you write on a piece of paper with a pencil like this, little particles of the graphite rub off and stick to the paper.

When you rub the eraser on the paper, it creates friction.

Friction creates heat.

Have you ever rubbed your hands together on a cold day to warm them up?

Try it.

When you rub an eraser on a piece of paper, the heat created by the friction warms up the material in the eraser and helps it become sticky enough to grab the graphite particles.

The molecules in the eraser are now stickier than the paper.

So when you rub the eraser on the paper, the graphite particles stick to the eraser instead of the paper.

Before erasers were invented, people used crusts of bread as erasers.

So let's try it.

It's kind of working.

It's definitely crummier.

Ugh.

And there you go.

If you have any more questions about how things are engineered, send your questions to the Design Squad website at pbskids.org/designsquad.