We had a bald half-senile history teacher in junior high.

We'd amuse ourselves on sunny days when conditions were right by using hand mirrors to reflect dancing beams of light off of his bald pate.

To our credit nobody ever got the dancing light into his eyes, or else he would have tumbled onto our little amusement.

My eighth grade math teacher was a very stern old lady who never went to college, but was a very good teacher.