How to do it

1. Try to fold different sized pieces of paper in half more than eight times.
2. Try it with a small piece and very, very large piece.
3. See! You can't do it!
4. Each time you fold the paper, the stack you are folding becomes thicker.
5. After a while, your arms aren't strong enough to fold it anymore.
6. It's kind of like trying to cut a thick stack of paper with scissors - you just can't do it if the stack is too thick.