Robert Frost was dropped from school for daydreaming. He was probably composing poems during some of his daydreams. ADDers daydream frequently, leading to inattention in classrooms and other dull environments. The conventional wisdom on ADD is that ADDers daydream because they can't pay attention, which isn't the whole truth. They can't pay attention to something which is boring .
ADDers are extremely, even painfully, boredom intolerant.
A daydream is more mentally stimulating, for example, than a grammar lesson, and ADDers require this mental stimulation more than others. Calvin is a smart kid who needs excitement, and school doesn't cut it. ADDers may actually be paying very close attention , hyperfocusing even, to their daydream. Leonardo da Vinci was famous for his paintings but only managed to compose 17 painting in 67 years, and some of those were never finished. Freud claimed that this was because Leonardo's father had abandoned him.