Lights! Cameras! Fractions! is a 1984 Disney educational live-action/animated short.
A group of junior high students (in live action) make stop-motion "cartoon" animated films. Kids watch their latest 16mm production in the classroom shot one frame at a time. You'll see Gumby-style claymation characters, plus a boy and girl flying all over the place. Later, they pretend to ride motorcycles down the street, all using 24 frames per second stop-motion cinema techniques. Afterwards, the students set up their next movie epic, using a 16mm camera on a tripod, lights, props, etc.