This has been the case for a long time. I was one of those kids who usually "got it" the first time I saw it, and then remembered it. So lectures usually moved much too slowly for me. In an effort to not be bored, I would usually sit quietly and read ahead in my textbook.

Some teachers were cool with this, but most of them would yell at me for not paying attention, and a couple specifically called me out for reading ahead on the basis that I thought I was too good for the class.