doitandhow.com; unfortunately this tree project links back to what appears to be a foreign site.
http://kidsartists.blogspot.com/search/label/winter Winter Glimpse Trees
Art teacher's blog post about this winter project, perfect for fourth grade students.
Shape monsters---can incorporate shapes, vertices and adjectives all in one. Have the kids create their shape monster then describe it using math vocabulary and afjectives
What's On Your Mind? Is a terrific way to get to know your students + these make an easy and awesome bulletin board too! Great activity for the first week of school and a nice ice breaker for students to get to know their new classmates.