When I first heard of the "fourth dimension" and knew it had some connection to time(I was maybe six or seven), I thought of it as an actual underground realm inhabited by dinosaurs and historical figures.
A childhood belief about general

others believed things like this
- i used to believe i could go back in time so i could see dinosaurs.Anon
- I believed you had to color all the dinosaurs in coloring books green because all the dinosaurs WERE green.— Betty
- For a very long time I believed that there were little men underground that changed the traffic lights!— Melissa
- For the longest time I thought Pig Latin was an actual language that they spoke in a part of Europe.Anon
- I used to believe that if you jump in a toilet, they lead you to another dimension.— beep.
- I thought the underground railroad was actually a subway.— Greg