Once when we were studying in biology class, when I was maybe 14 or 15, the teacher leaves the room and comes back with this sort of telly on the wheelie stand thing; he was trying to surprise us with an educational distraction from textbooks and, it was good on paper.
He must have forgotten to rewind the VHS or something, of a nature documentary, and the entire class got an immediate scene of two wildebeast trying to repopulate the Savannah by themselves.
I mean it did work, since it was a great distraction whilst he frantically Goku punched the Stop button as fast as he could, before pressing rewind.