When Is Homework Not Homework?

I asked James this weekend if he had any homework and he said, "No." So then I had to ask why his backpack was so heavy and what he needed his science book for. He explained that his teacher told him to bring the book home to study, but that's not homework. Somewhere in the process he must have thought he was carry those heavy books to build his muscles. I think he missed the point that the muscle he is suppose to build is his brain.