Why does looseleaf paper curl when I write on it?

Me, being an engineering student, I do alot of homework on looseleaf paper and pencil. I’ve recently had to buy some more paper, and I unintentionally bought some really crappy looseleaf. When i write and erase on it, the paper curls up from the bottom, which is really annoying!

My question is, why does the paper do this? It didn’t happen with my older looseleaf paper, which was better quality. And it only seems to happen when I write (or erase) on the paper.

Look at the other side of the paper. Can you see your writing as raised markings? If so, that’s the reason. You’re scoring the paper.

Newspapers didn’t used to curl either, before they switched to a thinner, cheaper stock. In your case, it’s probably the scoring effect, only noticeable with thinner paper.

Does it straighten out if you write on both sides?

Do you have sweaty hands? I had a similar problem when I was younger, and my hands were sweaty then. (I now have the opposite problem, b/c all the paper I handle dries my hands out.)