I found a slow motion video of a lynx leaping across a river, and kept pressing pause during different poses... and sketched it! Now I can get used to how this animal's body moves, in case one day I decide to paint it. This is a quick thing I did between breakfast and leaving for the day (while the spouse takes his time with tea). It's perfect for when you don't have a lot of time to play, but you want that time to be quality improvement time.
If I was doing that unpleasant sounding 600 page/month sketchbook challenge, this is probably much of what I would do with it. I think you could learn SO much about how the world works by recording how it moves.
Two people dancing
A dragonfly hovering
Somebody falling over
Ladybug taking off
storm clouds on a windy day
raindrops hitting the pavement
If you sketch enough steps, you can make an animation flipbook! What would you do?