Students self-selecting groups or the instructor randomly assigning students to groups are suitable approaches when the groups will only be intact for a short period of time and/or for low-stakes tasks. Having a go-to method for randomly assigning students is often useful, and there are a number of options that can be executed quickly, e.g., having students count off by the number of desired teams. For a creative twist on randomly assigning students to teams, check out this Geography-based approach used by Dr. Sarah Bednarz at Texas A&M:
"For short term groups (one or two classes), I frequently use random assignment, e.g., as students enter class they are given a card with an identifier such as the continents, islands, capital cities (geography examples in my case). Then, when it is time to form the groups, I can simply ask all the Antarcticas to move to the back of the room; all the South Americas to the front, etc."This example of group formation is one of several offered by the Faculty Teaching and Learning Portal at Texas A&M University; see more examples and an expanded discussion of team formation here. A Faculty Focus newsletter from last summer, "Better Group Work Experiences Begin with How the Groups Are Formed," highlights a few more quick ways to randomly assign students to groups (e.g., birthdays, last digit of cell phone number) as part of a comparison of random assignment, student-formed, and instructor-formed groups.
What about the students selecting their own groups? The research on this approach seems to be mixed, at best. For example, both van der Laan Smith and Spindle (2007) and Hilton and Phillips (2010) document the benefits to students when students are allowed to self-select groups (higher grades for high-achieving students and higher quality work reported by students, respectively) for accounting courses; however, the aforementioned Faculty Focus newsletter points out that trade-offs do exist. Students working within self-selected groups must grapple with the challenge of transitioning from social interactions to completing tasks and are not necessarily expanding their experiences of working with individuals they do not know. The observation from Hilton and Phillips (2010) that students are more likely to get to work immediately when working together with others that they already know may be advantage enough to overlook these potential downsides when dealing with short-term, low-stakes group situations.
Hilton, S., & Phillips, F. (2010). Instructor-assigned and student-selected groups: A view from inside. Issues In Accounting Education, 25(1), 15-33.
van der Laan Smith, J., & Spindle, R. (2007). The impact of group formation in a cooperative learning environment. Journal of Accounting Education, 25(4), 153-167.