What do you have in your head?
This idea come up visiting a behance portfolio of Akatre Studio, Paris, France - https://www.behance.net/gallery/23194649/Zero-To-Five-by-Akatre?isa0=1#
it would be a great project for photoshop classes, even illustrator:
what do you have in your head?
the people could take pictures of real objects over/in front their heads or make photoshop collages. if working on illustrator, they could draw objects, vectorize their own photos and create portraits.