How about planting a tree on the church property in honor of the teachers.
Invite them to join in the planting. The symbolism is RIPE! Give kids plastic shovels to "keep digging into the Bible and growing in faith." Take a photo of the event and include the names of all the teachers/volunteers and kids with it, and hang it in your "Heroes Hallway." This could be a whole new tradition and place to "grow." Bury some lesson "treasure" time capsules too.
Or...
Purchase bareroot tree seedlings to give to volunteers in appreciation of the roots they have helped establish and the gift of growth that will continue into the future. (Work that metaphor!)
