I am also pursuing my degree in education, and I was recently placed in a fifth grade classroom for a student teaching placement. The students in the fifth grade were working with recycling and they all created a recycling project which they presented to the class. The students could only use materials they had at home or that they found in the classroom (the teacher set aside some old materials the students could use).
The students really enjoyed this project and their creations were amazing! One of the students made a basket out of old magazines, it was unbelievably good. I was thoroughly impressed by their creativity and motivation. The presentation piece tied in some of the literacy standards we have been working with, too. You mentioned wanting to get the students engaged in recycling and this might be an idea for a project you could do in the future. The students you are working with are younger so maybe they could work in teams? Or bring the materials to class and work together to build their creations?
Since the school is not a big supporter of recycling this could be a way to show students the importance and fun in recycling. Once the students created their recycling projects maybe they could write a report or give a presentation to the school principal to convince them to push the school towards recycling more. I wish you the best of luck with your student teaching!