The groups were given two weeks to prepare and each group was to have five minutes of performing time. The groups were told that the assessment exercise was worth the same credit as a weekly quiz about 5 percent of the total grade. Furthermore, all members of a group would get the same credit- either full credit or no credit. The instructor arranged to have the performances videotaped for later viewing and brought extra copies of the checklist for the suudents to fill out as they watched the other groups. Each of the"human models" of vision was quite different from the others, and all were at least adequate. Two groups used simple costumes and makeshift props with members in rod" and"cone" hats, for example--and received much applause. The groups took their performances very seriously. but they also clearly had fun