My hand-drawn, 2D interpretation of the second Animation Mentor exercise: the light ball, heavy ball test.
My goal was to make the light ball so light that air resistance is a major factor in its motion.
This is animated on ones, twos, threes and even some fours and fives. One surprising discovery was that more inbetweens did not necessarily make the light ball look smoother or lighter.
I recall when I was in elementary school that every year they would show us Albert Lamorisse's "Le Ballon Rouge" (The Red Balloon), which I guess was their subtle way of teaching us it was bad to beat up on red balloons.