Why is there sand in my sand box?

Silly question, I know. But after observing Hayden for several minutes, I came to the conclusion that is what he was thinking today. We were outside playing. It was a little cold, but still a bright, beautiful day. I opened his sand box thinking he would jump in and play with all the toys. Not today. Today he was on a mission to rid the sand box of all it's contents. He quickly grabbed his little green shovel and started a monumental excavation of the sand. He got a scoopful and walked across the driveway to dump it in the grass. More times than not, there was no remaining sand in the shovel by the time he got to the grass, but that didn't bother him. The only thing that did bother him was that the dogs were interested in the sand as well. He told one to move. Well, really it was more like "moo!", but she got the idea and quickly got out of his way. This went on for several minutes when I decided to run get the camera. Of course, by the time I got back, he had moved on to playing with something else. It never fails!