Here's one my kids will be submitting in 20 years: at their elementary school there is an aquarium built right into the wall. Right next to it is a drinking fountain. Many kids won't use that fountain because they believe the water comes from the aquarium!
A childhood belief about classes

others believed things like this
- I used to think that Hadrian also built the Great Wall of China.— Spacey
- I used to believe that school was a place kids go to get turned into adults.— Samantha
- I used to believe that if i splashed water on the wall during a bath, the water would turn into spiders— justin
- In primary school, a whole bunch of kids including me believed that watermelon seeds contained ants. — Caff
- I didn't quite grasp the concept of time zones, and thought that Chinese kids went to school at night.— Giselle
- When I was in elementary school I use to think that teacher lived at school at their desks all year long.Anon