Couple more really obscure ones:
In Living Color (sketch comedy that ran on Fox in the early 90's) - there was one sketch where Tommy Davidson's character brings a C-130 built out of popsicle sticks to school (if I recall correctly, it was an art project), and the principal hassles him about it and ends up destroying it.
And then there used to be a math-oriented show for kids on PBS called Square One. At the end of most shows was 5-10 minute show-within-a-show called Mathnet, a takeoff on Dragnet where the two detectives used math to solve crimes. During one interview, the witness spends a lot of time fiddling with a pair of tweezers and ship in the bottle. As they're leaving, one of the detectives says something like "good luck with your model" and the guy replies something like "Oh, I don't put them in... I take them out", and just at that moment finally gets the ship to come out.