Another Snow Day....What are Some Activities You know of that are fun and also encourage learning?

For a lot of kids this winter, they have had so many snow days! In some districts, they have already gone over their limit. My question is how can a snow day be used for learning... instead of the kids being inside watching tv,  what else can they do, that is fun but also has more learning to it? I think I would encourage the kids to do some arts and crafts, or they could even talk to their parents about science- snow, weather, etc. And of course-  sledding is good for them too! . Any other ideas, suggestions?