For #2, gym is his last class of the day. This helps him to get his energy out and enables him to sit still on the bus for the ride home.
My boys are lucky also in that they do not seem to have inherit my bad knees. They should have no problems with all the activities they will be required to do for gym. While I loved some activities in gym, those were usually the ones that guaranteed to put me on crutches for a few weeks.
When I was about 13 or 14, I discovered I had what was known as a trick knee. I discovered this while running my dog through a snowy field. One minute I was laughing and having fun, the next felt like I had been hit by a high voltage electrical shock in my knee forcing me into a face plant into the snow. Not fun, let me tell you!
I would be walking along minding my own business and my kneecap would decide that it wanted to be on the other side of my leg. On its journey from the front to the back of my knee it tended to rip up all the muscles in its way.
To repair this, the doc's waited until X-rays showed that the bones had stopped growing (I was about 15 or so). I underwent surgery to put a stainless steel screw into my knee which was designed to keep my kneecap where it belonged. Post surgery I was in a couple different casts for a few months. Have you ever tried going into a public restroom with a full leg cast? It is quite an experience. I suppose the best benefit is that if there is no lock on the door you have a built in prop to keep the door closed!
It took about a year after the surgery to gain back the strength I had in the knee. I never regained full range of motion back. Where as before I was able to crouch completely down, it is now rather painful to do so for more than about 2 seconds. Also for some reason, I have never since been able to stand on that leg alone. I can stand on my left leg with no problems, but my right leg? Forget it. I suppose it is fortunate that I was not required to stand on my right leg or crouch down while in the Air Force. Nothing else is really an issue, just those two things.
The surgery did leave me with a 6+ inch(15 cm) scar running alongside my right knee. As I have never been inclined to wear mini-skirts(I don't have the legs for it), it does not really bother me. It actually rather matches the barbed wire scars I have on my other legs from my youth when I thought I was a bronc-buster, but that is another story.