As a parent, why is it that we can never remember that children do not always think as we do. The toys are left in the middle of the floor because that is where they are played with. It doesn't make sense to pick them up, You only have to take them back down again to use them.
The paired phrase - "May I go down by the stream?" "Yes, you may" is incomplete. If you don't say, "Don't go in the stream," he will. If you don't say, "Take your shoes off," they won't be. But they will be his school shoes and there won't be time to dry them out.