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Understanding Teacher Influence and Instructional Improvement

This Foundational Concept can be found in the following module pages:

First, what we do in classrooms influences what and how students learn, as well as how much they learn. Why else would we bother doing what we do (teaching, collaborating, leading)? Teaching is hard work because we want students actually to learn.

Second, we realize that students learn many things, at different rates, and in many ways. Whatever influence teachers have works on something that is already in play with students because students are born to learn! In formal educational settings, however, teachers have a special concern: to help student think with words and numbers; language arts, social studies, math, and science are typical tools for this activity.

Third, the mission of teaching is to help students become better and better at thinking with words and numbers in all those realms (called "academics"). We teach academics not for their own sake, but for the sake of thinking.

Notice that these three points are a logical chain: from an assumption (teachers have influence) to interactions with intellectually active students (they are always learning) to a result (students thinking better with words and numbers). In short, the idea and the fact of improvement is built into this logical chain and into what teachers do!

There's a lot of empirical proof that this is the case. The effect size (on student learning) for an average teacher is +.20 (Hattie, 2008). So, on average, teachers do have an effect on learning and students learn more! It's good news. But as individuals and as a team, we can do even better (and we want to do even better) than average. And the way we get better is by teaching better. If our discussions and decisions improved our effect size from average to above average (say, an effect size of .30 or .40), we'll have done good work.

"Effect size" isn't a complicated or subtle calculation. It's just one way to quantify (and then talk about) the size of an impact. Note that +.20 isn't a very strong effect. The fact that ordinary teaching has an effect of that magnitude tells us that there is room for improvement in every school and every classroom. So, teaching is important; and it has the potential to improve everywhere.

Still, a misguided fixation on test scores is hard to stop. Indeed, one common (and unfortunate) answer to "how to raise scores" is to adopt a product or a branded practice, especially one said to be backed by research. Many products have shown some effectiveness in relationship to test scores according to the Institute of Education Sciences's What Works Clearinghouse (2018). Using these products is what is usually meant by "evidence-based practice."

But using a product is just a beginning. No product does anything on its own, even if excellent studies show it to be somewhat effective. All implementation of products and practices requires the effort of teachers and students.


Hattie, J. (2008). Visible learning: A synthesis of over 800 meta-analyses relating to achievement. New York, NY: Routledge.

What Works Clearinghouse. (2018). What we do [webpage]. Retrieved from