Painting rainbows with mini-marshmallows to teach color order. Or for St. Patrick's Day.
10 Art Projects for Preschoolers
18 Fine Motor Activities for Preschoolers. Love how lots of these ideas use stuff you already have around the house.
Counting Snowballs from www.fun-a-day.com - A winter math activity for preschoolers. Easy to set up, with a lot of learning!