Katie was an exceptional 4th-grade teacher. Honestly, she was the single best classroom teacher whom I’ve ever witnessed. As she taught, she seemed to be tapping into multiple brains simultaneously, quickly analyzing what different students needed and responding in the moment to meet those needs. Add to that her warmth and humor, and her classroom was alive with learning.

I visited her classroom more than 20 years ago after multiple people recommended her to me. Her principal was effusive in his praise for her work and, as I arrived, he said one of his hardest jobs every fall was explaining to dozens of parents why their children would not be in Katie’s classroom that year.

As I was leaving Katie’s classroom, the other two 4th-grade teachers were in the hallway and summoned me over. At first, I thought they just wanted to say good-bye. We chatted briefly, then one of them asked me, kind of shyly:

What makes Katie such a great teacher?

I was a little taken aback by that question. Were they trying to figure out if I knew what I was doing? That wasn’t it at all. After a few more moments, I realized that they had no idea why their colleague was so often recognized for her excellence. They had never seen Katie teach.

I was dumbstruck. This trio had been colleagues for years. One teacher had worked in the classroom next to Katie’s for seven years; the other teacher had worked on the other side of Katie for nine years and in two different schools. Not once had either of them ever been in Katie’s classroom while she was teaching.

That encounter was really pivotal for me, one of those experiences that has come to shape so much of what I believe about teachers and teaching. At the core is my belief that teachers learn a great deal about how to work better as they work every day. They deepen their knowledge about students and teaching every time they step in front of a classroom. Although practitioners can learn a great deal from researchers of all stripes, practitioners also can learn a great deal from each other, especially when they have the opportunities and structures to do so.

As I drove away from Katie’s school, I thought about how demoralized her colleagues must have felt about being excluded from the knowledge that Katie could have shared and that might have helped make them better teachers. So near and yet so far.

I thought about the students in that school. Although it was wonderful that Katie’s students had the opportunity to learn from such an extraordinary teacher, her presence in that building did not help the dozens of other 4th graders in that school. Those children didn’t benefit at all from having this exemplary teacher in their school because her knowledge and her skills were never shared with her teaching colleagues. Didn’t those children also have the right to benefit from what was known by an exemplary teacher?

What of the several hundred other 4th graders in the other six or seven elementary schools in that district? Shouldn’t they also have been able to benefit from Katie’s knowledge and skills?

Years after visiting Katie’s classroom, I stumbled across a comment by Roland Barth, who said: I wonder how many children’s lives might be saved if we educators disclosed what we know to each other.

Keeping an exemplary teacher’s knowledge isolated inside a classroom isn’t just poor practice, it’s almost malpractice. If you want to be an agent for change in your school or your district, work now to ensure that no teacher works in such isolation. Be an advocate for sharing what you know. Ask to observe another teacher teach because of what you will learn. Invite others to observe you and offer you feedback on how you can improve. Write articles and make presentations about what you’re learning from your work.

By opening the doors to their practice, teachers demonstrate the value they place on their own learning and their belief that they have much to share with others.

JOAN RICHARDSON (@KappanJoan) is editor-in-chief of Kappan magazine.

Originally published in November 2016 Phi Delta Kappan 98 (3), 4. © 2016 Phi Delta Kappa International. All rights reserved.