I save up boxes of different types for when I want to do something different than having the children play with traditional blocks. The kids can also use the boxes saved not only for building, but use in the kitchen center to pretend they are cooking these things. They can use the boxes to store or group toys together. They can make play stores. This is just one way we use a open ended material. We have also used large boxes for the kids to have as a play boat to sit in and sing songs: like Row Row Your Boat. We have sat in boxes as a pretend home, pretend hospital, a pretend friend’s home, used them for a pretend vet. area for the kids to bandage their play animals. There is lots of things you can do with open ended material.