We've all had our favorite teacher. A teacher who has made a difference in our lives. And as much as our teachers want us to remember polynomials or the impact of the Industrial Revolution, the reality is that sometimes, we remember that teacher for the life lessons she taught us and how she made us feel, more than for what she taught.

A new study by David Blazar at the University of Maryland, College Park looks at teachers' impact on non-academic student outcomes, such as students' behavior, confidence in math ability, and happiness. Using student survey data, teachers have meaningful impacts on all these things, not surprisingly, with the largest impact being on whether students reported being happy or unhappy in class. This study echoes past research that looked at teachers' effects on non-academic measures.

What's more interesting is that teachers who had success in improving their students' non-academic outcomes were not necessarily effective at improving their academic performance. Teachers who were strong in one non-academic area were not necessarily strong in another. In fact, the study finds a negative correlation between teachers' effect on academic performance and their effect on students' happiness in class.

What to do with such findings? Is happiness more important than learning? Is students' belief that they are good in mathematics more important than actually knowing more math? It does suggest why some teachers—and parents!—may choose not to push their students too hard, at risk of losing their affection.

In any case, there's some truth to the old saying that people might forget what you say but they'll never forget how you made them feel.