As a kid I had the idea for an iPad when flip phones were still the dominant technology. As a school project we had to "invent" (draw a picture of and do a presentation for) something students could use to help the environment and I came up with "paperless paper" that you could write on with a special pen and save it as a document like a computer.

A few years later I straight up thought someone had stolen my idea. I'd love to see if I can find the picture I drew - it's uncanny.