I would create a lesson to 1. review copyright 2. show students how to find and properly cite resources for their class projects. CC is just one of many sites students can use to find resources for their work.
This can be used in conjunction with a ELA class when studying a classic novel. If a teacher need multiple copies of a book students could access copies via the Gutenberg site - allowing them to have access on any device they choose.
I would share this resource during a PD session with teachers - they can use to find all sorts of lessons about a variety of subjects and topics. It can be searched by subject, topic, and/or standards. Helpful when you are looking for a lesson.