When principals and coaches at Achievement First charter schools conducted observations this fall, they found that many teachers fell short when using a classroom technique called “checks for understanding.”

The technique, in which teachers ask questions to determine in real time whether students are absorbing lessons, “was the most important thing for improving our students’ achievement,” said Dacia Toll, Achievement First’s founder and co-CEO. Plus, she said, “We’re not asking good questions in the first place.”

So as the charter network’s annual professional development day approached, Toll took it upon herself to lead the checks for understanding session. That session, along with 48 other training workshops, took place Jan. 6 at a Marriott Hotel in Stamford, Conn.

Throughout her 90-minute session, Toll drilled the standing-room-only audience of teachers on how to ask targeted questions to ensure students understand the key points of lessons, and how to apply them. The group went over the basic techniques to ask questions — flash cards, choral responses, hand signals, pepper questions, cold calls, class sweeps, and more — and then debated which ones were better in certain situations. For example, Toll said cold-calling students would not be effective if the goal is to grasp whether an entire class understood a lesson. In that case, she said, “You’re only getting data from one student.”

Teachers said the content of Toll’s session wasn’t earth-shattering – many reported learning some version of Checks for Understanding during their regular certification process — but provided an important refresher.

“It wasn’t anything brand new, but it was useful,” said Lawrie Peck, a third-year teacher who started at an Achievement First school this year. “I think it was a great review of best practices that had kind of gone to the wayside with my hectic schedule and planning loads.”

Sessions during the professional development day covered a variety of teaching topics, from “SAT Editing and Revising” to “The Behavior Management Cycle” to “Having Authentic Conversations about Race and Class.” Connecticut’s new education commissioner, Stefan Pryor, who helped found Achievement First’s flagship school in New Haven, gave the closing speech to about 900 teachers from the network’s 20 Brooklyn and Connecticut schools.

Achievement First has brought its teachers together for an annual training day for years, but this year’s event came shortly after the network’s leaders collected new information about teachers’ strengths and weaknessnes based on formal observations. The network rolled out a standardized teacher evaluation model, called the Teacher Career Pathway, this year after testing it for two years. Teachers at the event gave mixed reviews to the system — which will be used to reward and promote teachers, as well as inform firing decisions – but Toll and co-CEO Doug McCurry, said it would primarily aid the network in “recruiting, developing and retaining great teachers.”

In his opening session speech, McCurry told the teachers that the evaluation system and other measures show that there is still a lot of work to do.

“Our reading scores just aren’t good enough,” he said, even though, as he noted, the network’s schools, on average, outperform their district counterparts. And, he added, “too many kids are leaving our schools.”

But there were brights spots that McCurry took a few moments to highlight. One of them was about a cluster of middle schools in Brooklyn, including Achievement First Bushwick, which received only a a short-term charter renewal because of its poor English language arts scores. McCurry attributed the poor showing in part to the state’s unexpected decision to raise test standards, but he said the schools also simply had fallen short instructionally.

“In some ways we felt like we got caught with our pants down a little bit,” McCurry said in an interview after his speech.

Last year, Achievement First Bushwick improved its ELA middle school scores last year by more than a dozen points while much of the rest of New York City flatlined. Principal Amy D’Angelo said the improvement came as the result of an “intensive effort to strengthen curriculum and instruction.” The school hired new teachers specifically to help English language learners and more aggressively tracked students who struggled with reading and writing.

“The big jumps we saw in ELA achievement this past year show that the improvements we made last year are working,” D’Angelo said.