Michelle, some things for you to consider...since you asked...
#1. The focus looks okay on my monitor, but you did crop her legs off, not a fan of cropped body parts, but that may just be me. Also, watch the background composition, that "hole" in the vegetation with the sky showing through tends to be a draw for the eyes. It took mine away from her eyes which is really where you want the viewer's eyes to go, at least I would hope that was your intent.
#2. Not too bad, again watch the background - big brown patch tends to be distracting. I am curious why the "orange thing" on the right hand side (as I look at the image) is so out of focus and again, it takes your eyes away from the the boy's face. Also, the bottom part of his forearm is cropped...see comment in #1.
#3. This is interesting because it takes the viewers eyes into the picture because both children seem to be looking at the same thing. I wasn't sure at first what the "white stuff" was behind them...when I first saw it (quick look), I thought it was water, but then I realized it was vegetation...not sure how you got it "white" (something in the conversion I assume), but it does provide a nice frame for the two of them and tends to "hide" the background a bit.
#4. This one is neat - my opinion. The young boy taking one last glance back at you looking like he is trying to decide if he should really go where the little girl wants to take him. I am wondering if this is a crop and whether or not there is more of the "dark" part at the top that you cropped. If not, I would think about cropping the dark part at the top and maybe some of the right side to get rid of a lot of the "brown" grass (if that is what it is). Alternatively, you could crop more of the left side off, so that they appear to be walking into the right side of the picture. Check out the "rule of thirds" for composition if you are not aware of it. Placing things "dead-centre" is a very neutral placement, whereas placing things off-centre can give the indication of action.
As far as focus goes, I have found that I can sometime lose a bit of the "sharpness" of some of my images when I shrink then down for posting on the web. I am assuming that you shoot raw, because if you don't, then a lot of the image is already processed in the camera and this processing is out of your control. The other question I would have regarding "focus" is whether or not you do any sharpening of your images, because if you do shoot raw, then most raw images do need some sharpening when they come out of the camera. HTH.
Cheers,
WesternGuy