In the fall, we used our fingerprints to make these fall colored trees. I have kept this hung up in the classroom all year, and wanted to add a tree for each season.
Here are the winter trees we made just last week. I traced the kids' arms/hand and had them color it with brown paint or brown marker (the marker was much easier!). Then, we put cotton balls, q-tips, and/or fingers into white and blue paint to make the rest of the tree. For some students, it helped when I drew a circle for them to fill with the white/blue paint.
Last winter, we did this finger print tree as a going away gift and I wrote each kid's name next to their fingerprint.
In the spring, I am planning on using this idea from Pinterest (could't find the original source). The kids use a soda bottle to create the blossoms on the tree.