In Huffington Post this week, I talk about a new movement of teachers who are taking control of their own professional development by seeking out rigorous cognitive and education research that can really help improve their practice.

One of the cornerstone works they cite is John Hattie’s Visible Learning and the Science of How We Learn. Any educator who hasn’t read Visible Learning — or the version Hattie wrote for teachers, Visible Learning for Teachers: Maximizing Impact on Learning — really should. Hattie and his team synthesized more than 800 meta-analyses of education research and found that almost any intervention will have some effect on student achievement. What that means is that almost any practice can gain adherents who can honestly say they saw a visible effect on their students.

That led to Hattie’s main point, which is that if we have any hope of helping all students learn to high levels, educators need to focus on interventions that have the greatest effect on student learning and not simply focus on anything that seems to help.

He studied quite a few things that many teachers think are important, such as lowering class size, and found modest — if any — effects.

So what did he find has the most effect of any educational practice? Providing rapid, accurate, and helpful feedback to students.

That finding isn’t flashy, but it goes to the heart of teaching and affirms the impact teachers can have when they focus on providing quality feedback.