Thanks for the input, Pemberly. Your dd sounds so fun! We have added challenge to ds' "homework". For example, he was supposed to look at a beginner book and count how many times he saw the word "and". We translated that to an advanced short story instead. They were asked to "count to 20", so I had ds to this by ones, twos, threes (or nearly to 20 :), etc. There is very little communication about what they do in school, so it's hard for me to know how to supplement. He is science crazy and in love with maps, so we are constantly doing enrichment at home, just not sure how it compliments school.