The use of manipulatives (including food) in computer science education has become increasing popular [1,2,3]. In fact, Davis and Rebelsky [4] (and others noted in this paper) have made algorithm design more accessible using peanut butter and jelly (PB&J) sandwich preparation. This experience report looks at how to use PB&J to induce student reflection on the roles of the observer and the observed as part of the design of a user interface.

The paper is easy to read, with a few photos to convey the practicalities of the activity. More importantly, the authors present clear goals, along with a section on what parts were effective and the parts in need of improvement.

There were two unexpected results reported. The first one involves the importance of thinking aloud as part of the observation process. It would seem that such talking would detract or interfere with the learning of the class as a whole. However, this report makes a case for having each student articulate his or her experience during the activity. The second surprise involved the participation of international students along with US residents in the classroom. Specifically, PB&J is a native object for many students, but not for all. The authors claim this feature of the class inspired discussion, not only on issues of cultural background, but also on the relative expertise between the observer/observed pair.

This experience report is worth the short amount of time required to read it.