I believe I saw this somewhere between the mid and late 1980s. Possibly very early 90s at the very latest. Saw it on TV, so I’m not absolutely sure if it was a movie or TV show. I think it was a movie, though. There was a teacher sitting at his desk in front of a classroom of students. For some reason, the teacher pushed a button, and a panel opened up on the front wall, exposing a video camera. I think it was in response to suspecting that somebody was cheating or something. Somebody in the classroom may have been fumbling with a cast on his arm, and may have had something hidden in it. That part is fuzzy, but I definitely remember the video camera part clearly. Any ideas?