A group of children were playing with some yarn. We'd been making telephones using paper cups and yarn. One of the children had the yarn twisted around his finger - we all seem to need to have that experience when we first play with yarn. The yarn was around the OHP. As I was helping unwind the yarn around the finger there was a CRASH. One of the children said that he saw smoke coming out of the OHP. The glass shards were fairly large so I picked them up, told the children to stand back and helped them move their play to another part of the classroom. The OHP had stopped working. We will try to repair it. (The OHP works. We're waiting for a new piece of glass and we'll be back to light experiments).