How many students should be in a group?
The short answer: pairs and threes for thinking and problem solving, fours for tasks with roles, and five or six only when the task is big enough that everyone has a real job. The larger the group, the harder it is for every student to have a turn and for you to see who is contributing.
The arithmetic of a group
Two things grow quickly as a group gets bigger.
Relationships to manage. The number of pairs of people in a group of n is n × (n − 1) ÷ 2.
| Group size | Pairs of students | Talk time each in 5 minutes (if shared equally) |
|---|---|---|
| 2 | 1 | 2 min 30 s |
| 3 | 3 | 1 min 40 s |
| 4 | 6 | 1 min 15 s |
| 5 | 10 | 1 min |
| 6 | 15 | 50 s |
In practice talk is never shared equally, so the quieter students in larger groups often get far less than these figures.
Places to hide. In a group of two, everyone is visible. In a group of six, a student can contribute almost nothing without anyone noticing. Research on social loafing found the effect to be moderate in size and widespread across tasks, and found it reduced when each person's contribution can be identified (Karau and Williams, 1993). Smaller groups make contributions easier to see.
What the research and practitioners suggest
- Cooperative learning guidance from David and Roger Johnson generally favours keeping groups small so that individual accountability is easy to see. Two to four students is the range most often described.
- For problem solving in mathematics, Peter Liljedahl recommends groups of three working together at a vertical surface, formed at random and changed often. His recommendation of threes comes from his own classroom research over several years, and it is a recommendation for problem solving, not a rule for every task.
- For literature-style discussion, many teachers use four to six students with defined roles. See group roles in language arts. The roles do the job that small size does elsewhere: they give everyone a part.
- For stations, groups of three or four fit the materials and keep every student busy. See learning stations in math and science.
Evidence note. There is no single research-proven number. Group size interacts with the task, the age of the students and how well they have been taught to work together. The figures above are well-supported starting points to adjust from, not rules.
A guide by task
| Task | Suggested size | Why |
|---|---|---|
| Quick turn and talk | 2 | Everyone speaks, nothing to organise |
| Solving a problem or building a model | 3 | A third viewpoint without room to hide |
| Hands-on work with shared materials | 3 to 4 | Everyone can touch the materials |
| Discussion with assigned roles | 4 to 6 | Roles give each student a part |
| Debate | 2 sides, split into smaller teams to prepare | Prepare in small teams, then argue as sides |
| Jigsaw expert groups | 3 to 5 | Enough minds to learn the piece, small enough to teach it |
When the numbers do not divide
A class of 31 will not split into neat threes or fours. Options that work:
- One group a student larger or smaller than the rest. A class of 31 in fours is seven fours and a three.
- A trio instead of a pair for partner work.
- The teacher as the partner for one student, which also gives you a close look at their thinking.
- Absent students change everything. Re-check the groups when attendance changes, because a plan for 31 may be 27 today.
Try it with ClassMixer
ClassMixer sets group size to your class and the day's attendance. Choose "groups of 3" or "groups of 4" and it splits the class as evenly as possible. For partner work with an odd number it can pair the leftover student with you. It also remembers who has worked together so students meet new people.
References
- Johnson, D. W., & Johnson, R. T. (2009). An educational psychology success story: Social interdependence theory and cooperative learning. Educational Researcher, 38(5), 365–379.
- Karau, S. J., & Williams, K. D. (1993). Social loafing: A meta-analytic review and theoretical integration. Journal of Personality and Social Psychology, 65(4), 681–706.
- Liljedahl, P. (2021). Building Thinking Classrooms in Mathematics, Grades K–12. Corwin.