We made some great spinners:
When we spin the pencils we can see
a fish in a fishbowl
an astronaut on the moon
a dog in a kennel
a bird in a birdcage
a monkey in a tree
a lion in a cage
This is because our eyes are faster than our brains
so we see both pictures one at a time
but our brains can't go that fast and so they think we just see the two together.
This is fun to try!