Object: the sun.

Boys and girls, let's pretend for a little bit today. I want you to pretend that this morning, for no reason that anybody can figure out, the sun did not shine. What would that be like? (Let them offer some answers.) Actually, you might not even wake up if the sun didn't shine. Isn't that right? Some people use the sun for their alarm clock. When the sun comes in the window, they get up.

But that might not be a big problem. We would probably wake up sooner or later because we usually wake up after we have had enough sleep. What would be the next problem without the sun shining? Right. It would be harder to find your way around. If you went out to get…