• What a nice piece of work!
• The background is very well handled. There are nice warm colors the offset the cold feeling of the winter scene. I personally feel that backgrounds should be done in an impressionist way with a blurry look so the viewer's eye can focus on the main subject more easily.
• The painting is well simplified. You didn't get carried away with unnecessary detail. In general snow scenes allow for this. The snow blanket takes away the burden of having to define the ground.
• There is nice gradation from a darker foreground to a lighter middle ground, thus conveying distance.
  

There is very little to say in the way of improvement.

We artists should devise ways to keep viewers from wandering out of the painting by creating visual paths that lead us into the painting and not out. If you look at your original painting you will see that we have what seems to be a frozen stream. If we follow this visually we will enter at the bottom of the painting. As we follow it, it takes out right out of the painting at the right side.

If possible try to avoid placing odd numbers of elements in the center of interest. We have two children. Fortunately their body positions are so different that they aren't really competing for attention. The dog gives an intention of neutralizing this dualism but I feel it was stuck in there the last minute. If you relocate the dog and put it behind the standing figure looking inwards probably at the seated figure we will have three figures as well as include the dog rightfully. This would also hold your eye in the picture. Be careful not to place anything interesting at the borders of the picture plane. Just the fact that the dog's head is there will grasp our attention.

I turned the frozen stream inwards. Now it seems to engulf the boy who is walking. I took the dog out, now we seem to focus more on the children.

Additional comments:

Excellent job - keep up the good work!