#1 the lighting is a bit flat and its coming from below his face as you can tell by the catch light. If he were laying the other direction so it was coming from above and you shifted your angle slightly it would be a lot more pleasing and not so flat lit.
#2 is a good shot but it looks a little soft like it might be out of focus a bit. Always try to get that focus sensor right on the eyeball to ensure sharpeness. And keep in eye on your shutter speed. I am not sure what mode you were shooting in but for kids the best mode is aperture priority. Your deptch of field will always be a constant and by keeping an eye on the shutter speed if your shooting wide open and you drop below 125th of a second you can bump your ISO up a bit to compensate and get your speed back.
#3 is ok, I am just not a fan of squinted or no eyes showing. Good shots though, I am sure they will get better with repetition.