Today Case tried sitting up on his own. It only lasted a couple of seconds.
"Yeah, I do things. So what."
The other day he actually got his belly up off the floor a few times and scooted. I wouldn't really call what he does crawling because the movements and direction are pretty haphazard but he is moving! The other day he went from the middle of the living room to the kitchen tile!
He interacts with toys now. He even reaches for them on his own.