keep your elbows in on bottom would keep his opponent from getting wrist control. To get out of an arm bar, you can do kind of a swimming motion to get your arm free - The side that he opponent has the arm bar on, bury that shoulder into the mat, slide the same side knee up, while keeping the other elbow in (so opponent can't get a half nelson) and then a short swim motion to get the arm free. Another option is when the kid gets out to the side to run the arm bar over to pin him, stand up. His opponent's weight isn't on him anymore and its usually pretty easy to come up and escape the arm bar.

Always keep your elbows in on bottom, always try to stay in a good base, while trying to escape. Pinning someone is a lot harder to do if they keep their elbows in, they have a good base and get hand control to stand up.

He can free his wrist from his opponent's grip by reaching his other hand under his opponent's wrist, grabbing his own forearm just above the grip, and prying it off with the back of his own wrist.