I used to believe that the "long run" was an actual race. When I was 7 I spent the whole summer running back and forth in the yard because I thought the long run was part of the gym curriculum in the coming school year.
A childhood belief about speaking

others believed things like this
- When I was in elementary school I use to think that teacher lived at school at their desks all year long.Anon
- I used to believe that coin change could turn into actual paper money if you left it alone for a long time. — Marcus O
- I thought that 1983 went on for 3 years - had to ask my sister who decided how long a year lasted.— Sally
- I used to believe that at the beach town where we spent the summer, they took the sidewalks in for the winter.— Missy
- For the longest time I thought Pig Latin was an actual language that they spoke in a part of Europe.Anon
- My sister thought (not more than one year ago, she is now 14) that John Doe was an actual person.— Brother to Natascha