In Messy: The Power of Disorder to Transform Our Lives, Tim Harford discusses heterogeneous vs. homogeneous teams. He cites a 2009 study where college students were given the task of solving a murder mystery problem. Some of the groups were composed of four friends, others included three friends and a stranger.

The groups that included a stranger were much more effective at solving the mystery. 75% of the time, they came to the correct conclusion. The homogeneous groups correctly solved the problem only 54% of the time, while people working individually were successful only 44% of the time.

Interestingly, Hartford writes, the participants in the heterogeneous teams “didn’t feel very sure that they’d gotten the right answer” and “felt socially uncomfortable” [p. 50]. The homogeneous teams “had a more pleasant time” and (falsely) were more confident they had found the right solution. In other words, the team members’ perception of how their team performed was out of sync with their actual performance.

The diverse teams were more effective, but that is not how things seemed to people in those teams: team members doubted their answers, distrusted their process, and felt that the entire interaction was an awkward mess. The homogeneous teams were ineffective and complacent. They enjoyed themselves and wrongly assumed that because their friendly conversation was smooth and effortless they were doing well. Messy: The Power of Disorder to Transform Our Lives by Tim Harford, p. 50.

The debate about team formation in K-12 education continues to thrive. In this Edutopia article, Ben Johnson argues both sides, but ultimately concludes students blossom more in homogeneous groups. In 10 Reasons to Use Heterogeneous Teams, Dr Spencer Kagan argues for only heterogeneous groupings.

In education, we often look at grouping through the wrong lens, wondering how effective it will be to put students with different abilities in the same group. My hackles raise with the term “ability,” since it is based on a questionably valid definition (and data) as to what “ability” means. It also assumes a steady state, in other words that a student will always have the same level of “ability.”

One way #PBL (project-based learning) shines is that it accepts (just like the #realword does) that each student has different assets to contribute to a team. When (heterogeneous) teams are formed, the key to success is in identifying which role(s) fit each member of the team based on their unique talents and skills. As they succeed in the given role(s), students develop confidence and a growth mindset, the understanding they have the power to become ever more accomplished learners.