To facilitate a fair challenge, have students send their mashups to you anonymously so the class is unaware who is in the photo mashups. Also encourage students to use object photos or people that blend best with their friend so they are unrecognizable. If you feel some students will be more recognizable than others regardless of fractional parts selected, you can offer students four preselected photographs that everyone has to mashup for the challenge.

This is particularly useful for Lessons such as Hidden Face Challenge.