That's very true. I went to a state school with some ADHD kids who had been transferred in from other parts of the country? What triggered them? Boring lessons. History teacher who would make the class spend the entire hour just copying down notes from the blackboard. No discussion, just copy, copy, copy, then go to the next class. If you were lucky you managed to copy everything. If not, too bad. Language lessons would have everyone just stare at an overhead projector screen with pictures of things and their foreign language equivalent. And we'd go through these one after the other.
Science teachers had a better way. You got laminated work cards that told you exactly what to do. Copy this paragraph, do this experiment, take these measurements, what conclusions can you make? If you didn't get all the work done in time, you took it home with you.