Pinecones are an easy item to craft a bird feeder with. As a matter of fact, if you use a natural cotton or hemp twine to hang them in the trees, you may have an entirely biodegradable product that will not require clean-up later.
Pour birdseed onto large baking sheets. Line the baking sheets first with parchment paper if you want an especially easy clean-up. Then, instruct your students to spread peanut butter on the top of each pinecone "leaf" with a spoon or dull knife. Each student rolls their peanut butter & pinecone creation in the birdseed.
The last step is to tie natural, biodegradable string or twine around the top of each pinecone, and find appropriate places in the trees to hang them.