The results: Their average scores were 2 percent higher than the previous year’s, and not because of the bonus points. We’ve long known that one of the best ways to learn something is to teach it. In fact, evidence suggests that this is one of the reasons that firstborns tend to slightly outperform younger siblings on grades and intelligence tests: Firstborns benefit from educating their younger siblings. The psychologists Robert Zajonc and Patricia Mullally noted in a review of the evidence that “the teacher gains more than the learner in the process of teaching.”

I had been trying to teach this lesson through my research on givers and takers, but it was so much more powerful for them to live it.

Creating an atmosphere in which students want to help one another also allowed them to benefit from another of the defining features of personal and professional relationships: transactive memory, which is simply knowing who knows best. In a marriage you don’t need to know how to fix the air-conditioner if your wife does. In a work team you don’t have to know how to perfect PowerPoint slides if your colleague is an expert.

Even in the world of finance, where success is supposed to be about raw brainpower, research shows that star investment analysts who join new firms see their performance drop for the next two years — unless they take their teams with them. It takes time to learn who knows what. Transactive memory makes it easier to ask for help — you know where to turn.

When students take the time to find out who has expertise, they become smarter at learning. And that’s ultimately what we’re trying to teach, isn’t it? The mark of higher education isn’t the knowledge you accumulate in your head. It’s the skills you gain about how to learn.

By 2014, before the final exam, a student sent an email to the entire class announcing that she and a friend had reserved a room for Saturday afternoon studying, and anyone was welcome to join them. That night, another student suggested that the class could divide up the readings and write summaries. Two minutes later a third student responded: He had already taken the initiative to write a comprehensive study guide, which he shared with the entire class. Many students contributed their own insights, and one even made a practice quiz — a smart idea since it’s well established that testing is a better way to learn than regular studying.

That year, the scores climbed another 2.4 percent. “Your class has changed the way students work together,” one student wrote to me. “I’ve never seen a group of students so willing to help one another succeed.”