I used to think that if a near-sighted person held a mirror and viewed the reflection of a distant object, they should have no trouble seeing the object in perfect focus. After all, they're looking at the mirror, and it's only a foot or so away.
A childhood belief about physics

others believed things like this
- I used to believe that when you cracked a mirror your reflection would come and take over your body!— XxXAbbeyXxX
- I used to believe that my reflection in the mirror was my evil twin that always had bad hair. XDAnon
- If you stare into a mirror in almost complete darkness, the devil will appear instead of your reflection.Anon
- When I was little I was conviced if you said twinkee in a mirror 3 time a foot would appear. Anon
- when i was young i used to believe that my image on a mirror would come to life if i broke the mirror.Anon
- I used to believe that there was a person in the mirror who looked exactly like meAnon