Here are some ideas to create and modify for your older grades:
This link offers a version of the project that would be awesome for middle grades/high school/even adults!
My name is Robin Norgren, M.A. and I am here to help make Montessori philosophy more relevant in the classroom. My projects include: Josey's Art School, The Gifted Learner, Creativity and Wonder and A Montessori Way of Seeing. I found my way into educational spaces as a mother of Creative children yet I am not an art teacher. This information is important because my style empowers teachers who are shy about teaching art but looking for products that promote expression over technical perfection.