Over the past couple days I've noticed that Jack is much more in control when he's sitting on my knee. I still have to hold him up, but I can feel the strength of his back and his head doesn't flop around much at all anymore.
Also, he's really able to grab things with his hands now. It started with this beautiful wooden rattle that Sean's friend Joel gave him (made by the Haessigs in Spooner, WI!). It has a great shape and it was the first thing that he could really solidly hold in his hand. Yesterday and today I held it out and shook it and Jack looked up, looked at the rattle and after a couple of tries, got ahold of it. It's much less of a hit or miss than it used to be.
I try to give him lots of free form time on his back and stomach so he can understand his body and how it moves. Today he was clearly using his arms, although he didn't quite understand how he was supposed to use them. He kept his head lifted the entire time he was on his stomach. I cheered him on.
I think it must be a drag to be a single parent and not have a partner who is as interested in every mundane detail of a child's development as you are.