Editor's Note: Lemov is the co-author with Erica Woolway and Katie Yezzi of the book, "Practice Perfect: 42 Rules for Getting Better at Getting Better."

Recently, a teacher we admire, Maggie, noticed something about her classroom work that she wanted to improve. She taught reading to sixth graders at Troy Prep, a school in the city of the same name that is run by Uncommon Schools, the organization where we work that starts and operates urban charter schools.

Maggie took great pleasure in reading literature with her students -- "Anne Frank: The Diary of a Young Girl," "Esperanza Rising," "The Westing Game." Her students, 96 percent of whom were eligible for public assistance and who previously were unsuccessful in school, thrived in her literature-based approach. They became fluent readers with expanded vocabularies and developed a passion for reading. They scored well on the state test, outperforming the district and comparable schools.

Maggie could have rested there, but like so many teachers, her personal standards were higher. She wasn’t happy with what happened when a student gave an unexpected or unpredictable answer to a question during a discussion. She’d get anxious. Sometimes she would react by providing the correct interpretation herself, cutting off the discussion among students and crowding out their thinking.

At her principal’s suggestion, she began working with a fellow teacher, Nikki, who was especially adept at handling discussions. They decided to do something mundane and powerful. They decided to practice. Three or four times a week the two teachers would spend 10 minutes asking each other questions from their lesson plans. One would ask and the other would pretend to be a student who got the answer wrong.

The first teacher would have to think on her feet, responding with a question that would gently prod a student toward understanding. Sometimes they got it right, sometimes wrong. Sometimes they would brainstorm alternatives and try again.They gave each other feedback, both positive and constructive. They switched roles. They laughed a lot. It was fun and sometimes silly but also safe and they felt sure it was making them better.

Surprisingly quickly, Maggie saw a difference in her classroom. Discussions improved dramatically. They became more rigorous and students owned more of the thinking. Maggie felt more confident about holding discussions. She knew how to react so she planned more of them. With the skill of running discussions now almost automatic, she could focus more on who was participating or what to ask next.

What Maggie and Nikki did was smart and highly unorthodox -- smart because it recognized that teaching is like a live performance. You can’t pause and call a colleague for input if things aren’t going well, and even a triumphant performance one class guarantees nothing about the next. And it was unorthodox because teachers generally don’t practice. Other professionals who perform for a living understand the importance of practice.

Imagine a tennis player walking onto center court without 10,000 refining backhands or a cellist entering a stage without the scales still echoing in her ears. If we asked a room full of teachers how often they practice their moves before they perform, they might look at us funny. Teachers think about their work. They talk, reflect, read, analyze and discuss. But they don’t practice. And this, we have come to believe, is an immense oversight.

Carefully designed practice, similar to what Maggie and Nikki used, can help people improve by developing core skills. It can also cause them to get better at implementing feedback. Further, practicing can make a sometimes lonely profession into a team sport by bringing together teachers who often work in isolation.

Nikki and Maggie’s story doesn’t end there. Their principal shared the activity at a training session in which the rest of the school's teachers paired off by subject area to practice responding to unexpected answers with positive results. They now do it regularly. And as trainers of teachers, we observed Nikki and Maggie in action and used their drill with 200 teachers from district schools in Houston.

As they worked energetically to improve their classroom performances, we had the distinct sense that we were looking at the future of our profession -- one where the phrase “professional development” is replaced with the word “practice.”