During the past month, Mason has been an avid explorer of his bedroom and our living room. He is learning to crawl! At first we thought this would be a good thing - he could follow us around, and we wouldn't have to pick him up all the time. But now we are beginning to realize it might not be such a good thing after all - he no longer stays where we put him! He can easily scoot across his bedroom, and he is doing pretty good in the living room, too.
He isn't really crawling on his hands and knees though. He pulls himself along with his arms and hands. It's more of an "Army crawl." 
He hasn't quite figured out how to get those knees and legs going. Once he gets up, he usually falls flat again. But it won't be long . . .