When Dan Crispino took the job overseeing the curriculum for elementary schools in Meriden, Connecticut, it was 2019 and he had a big problem to solve. The low-income district, where nearly 75% of kids receive free or reduced lunch, was struggling with math.

“When I would go into classrooms all over the district, I could see that kids didn’t seem as excited about math,” Crispino said. “And it didn’t surprise me that our results were depressed in math.”

Crispino said math classes were 60 minutes then. They are now 90 minutes, beginning with a 30-minute lesson followed by an hour-long block where every minute counts. The class is made up of tightly timed segments, where students and the teacher rotate through small groups.