In 9th grade I had a math teacher whose concept of teaching was to tell us students to turn to page X of our math books and do the problems from page X to page Y. In the meantime, numerous strangers would come and go from the classroom and we could see money changing hands. The school district gave some half-a$$ed explanation that this teacher was in charge of the milk fund and was paying the vendors when a delivery was made. In reality, the teacher was a bookie.
The teacher was never disciplined or fired. He was some minor official for the local Democrat party, and in this town, corrupt Democrats rule.