At 2nd grade, I changed schools, and in the new school, they called the toilet the "lavatory". I had never heard the word before, and I thought they were saying "laboratory". So on my first day at the new school, when kids said, "May I go to the lavatory?", I wondered where they were going.
I reasoned that if everyone wanted to go there, it must be some kind of room with toys.
After about a week, I finally figured it out. Boy, I was disappointed!
A childhood belief about speaking

others believed things like this
- In first grade, I thought that if I've never heard of a word before, then it wasn't a word.— Destiny
- When I was a kid, I believed that bible school was "beauty school", and called it that all the time.— Dana
- i used to believe that everyone was born as the opposite sex, and that you changed when you started school.— llama
- A[n] nth grade teacher only had to finish the nth grade when he or she was in school.— MD Caruso
- I didn't quite grasp the concept of time zones, and thought that Chinese kids went to school at night.— Giselle
- when i first started school i thought the teachers lived in the school and slept on the tables.— emma