I remember an exercise in class where we had to measure the length of our foot with a 1-foot-ruler. I was absolutely confused as to why we needed to, since a foot must be a foot long!
PS - By the time I was older I was actually quite gifted at mathematics - true.
A childhood belief about classes

others believed things like this
- I used to belive that if i put my foot in my mouth, I would get foot-and-mouth illness— Emily Sathrota
- When I was little I was conviced if you said twinkee in a mirror 3 time a foot would appear. Anon
- When i was little i used to think that my foot was a "naughty part" that no one else was supposed to see.Anon
- when i was 6 i used to belive if u ate ur toe nails u would grow a foot in ur stomach— chris
- that using athletes foot cream would instantly make me an athlete. — Kate
- I used to believe that dandelions where baby lions and if you trod on one it would bite your foot.— alice