This problem will engage children as it can be done practically. It is a good opportunity for talking about ways to work systematically.

Which ways of folding have you tried so far?

How will you remember what you have done?

How will you know when you have got all the ways?

It would be helpful to have lots of bits of scrap paper for children to fold. They can then use a new sheet for each new fold which will allow them to compare the different ways more easily.