We've just started working into a little homeschool preschool schedule with DS and he (and I!) are really interested in nature. With several feet of snow on the ground over here it's been a bit tough to do what we really want to do which is go for a tromp in the woods. We've been reading several picture books about winter/seasons including Sybille Von Olfers "Mother Earth & Her Children", which has my son interested in all the things going on under the snow right now. Any recommendations on good nature books/books that encourage nature study (or curricula?) for this age group?