Paramecium?

A science teacher brought his 3 year old son to school with him, so he could show his son what he did. While teaching class, his son said. "Look Daddy a paramecium!". The father and all the students were astonished that a three year old new a large word like that. Then they noticed the boy pointing to the back of the room. He was pointing at a cage with 2 white mice in it. And said again, "Look Daddy a pair of meice see'um".