A shout out to Sonita, who has put a lot of thought and experience into this post.
Of course back in the day, children were either homeschooled, had a governess or tutor if they were rich, or went to the one-room schoolhouse. My grandmother recalled listening to what the teacher was doing with the big kids and picking up a lot, no doubt at the cost of what she was supposed to be doing at the time.
Whatever, there was more than one age of kid being educated together. Just a thought.
Even with busy work, there is probably way less downtime than in the average public school day, YARTHS!