A children doing schoolwork. (Ankur Khator/Ankur Khator)

We often hear about or see for ourselves teachers who have major weaknesses. The thing that hinders so many, it seems, is that they rush through lessons too fast without stopping long enough to see whether everyone — or anyone — understands. They might ask a quick question of a student or two to determine whether the main points registered, but that’s it. They must stay on schedule. Our schools have standards that demand a lot of material be taught.

Checking for understanding is difficult. How to do that has puzzled me, until I opened the latest book by Doug Lemov — the best writer on teaching techniques I have encountered. He has collected dozens of ways from successful urban classroom teachers to keep a lesson moving, but not so fast that students don’t absorb what is being taught.

Lemov’s 2010 book “Teach Like a Champion” has sold more than 800,000 copies. Never before has a book had such detailed descriptions of proven ways to handle students who don’t respond, who hide their confusion, who have trouble listening or who suffer from other classroom maladies.

His new book, “Teach Like a Champion 2.0,” is an impressive volume, with 473 pages of intricate advice backed by a DVD that lets readers see how 62 techniques are applied in class. At first, I thought it was too much like the first book to merit a column. Then I got into it and saw what it revealed about how to tell quickly whether students are getting what the teachers are giving to them.

Lemov is a former English and history teacher who is now a managing director of UnCommon Schools, one of the most successful nonprofit charter school networks in the country. It has 42 urban schools preparing more than 12,000 low-income students in New York, New Jersey and Massachusetts.

If a teacher prepared several quick questions in advance of giving a lesson, he says, they could be used to get a much better picture of student understanding. “You can maximize how much you learn by being intentional about choosing to whom you direct questions,” he says. “Ideally, in asking five or six questions, you’d call on your best guess of a statistical sample of the students in the room. Two students are usually around the middle. Two perhaps who tend to take a little longer to master the content. Perhaps one high-flyer.”

A teacher could also be “cold calling,” which means asking questions of students who don’t raise their hands and are less likely to have paid attention. “Be aware, though,” Lemov says, “that it’s important not to limit your cold call only to when you check for understanding. You want to cold call before — and frequently — so that you normalize it, and students aren’t surprised when you use cold call as part of your targeted questions.”

The teacher points out errors, but more importantly creates a culture in which students are praised for confessing their own errors. That makes it much easier and quicker to determine which students are wrong and why, essential to helping everyone understand, Lemov says.

Lemov told me he was motivated to write the second book by seeing teachers take the ideas of the first book and make “them more rigorous and better than what I imagined. . . . Teachers are underrated as entrepreneurs and in this case they entrepreneured me into having to write a totally new book.”

So much is happening in classrooms today, rarely illuminated except by people such as Lemov, who watch very closely.