Fantastic way of mixing things that shouldn't work. Experimentation is key with collage. I don't like creating collages without the main images being my own work, but it could be interesting to incorporate other work, old photographs, sketches, patterns etc
Paper Collage. Have each student paint several sheets of watercolor paper in tints & shades of a single hue. Add textures. The finished papers will be contributed to a selection of papers which all students can share. Students might create collages using the shared painted papers. This example focuses on complimentary colors blue and yellow-orange.