I don't require workbook activities or sit down "classroom" type lessons, but I let them take in the freedom to learn what they are truly inspired by. Last summer, that meant creating a "perfect habitat" in the yard for a lizard, swimming safety in a lake as opposed to the pool, lake creatures and rocks, etc. We went to a Farm Sanctuary, a museum of play, a goelogical museum and other places. From there, curiosity led to a desire to know more and seek learning. It was great!!
Hoping for another summer of the same.