Beautiful children!
1) I would boost the "warmth" of tones in this picture- the blues seem a bit too dominant, maybe the blue of the playground equipment was reflecting "blue-ish" light onto the child's face? It's a darling shot, but it seems the camera chose to focus on the object closest rather than the boy- to my eye it looks like the slide is more in focus than he is. I'd like to see more of him in the frame, less of the slide.
2) I like this one much better than the first

His lovely eyes are in great, sharp focus, and the skin tones look much more natural. None of the fake blue light here. What I think could make it a little better, is having him less "dead center" in the shot... It's a sweet picture of a beautiful little boy- but it doesn't hold my interest. Also, something about the shadow seems off.. Is that part of the playground equipment, or am I seeing your shadow in the frame?
3) LOVE this one! Great job on using the forground to frame your subject! It really draws the viewer in to the child, and (his/her?) eyes. It really makes you wonder what the child is thinking about

I think maybe boosting the "warmth" of tones would befefit this shot as well, but the blue-ish color isn't as dominating or distracting as in the first one, so it really does work well with the overall mood. The third one is worth of framing IMO =)
Looks good! Most importantly, how do YOU feel about the pictures? Did you have fun?