Green attributed the improvements to an approach that engages students more in their classes.
"Kids want to take an active part in the learning process," he said. "Now teachers are actually working with kids."
Although the method has been more popular in high schools, it's now catching on in elementary schools, said Afstrom of the Flipped Learning Network.
Fifth-grade teacher Lisa Highfill in the Pleasanton Unified School District said for a lesson about adding decimals, she made a five-minute, how-to video kids watched at home and in class, then she distributed play money and menus and had kids "ordering" food and tallying the bill and change.
A colleague who teaches kindergarten reads a storybook on video. The video contains a pop-up box that requires kids to write something that shows they understood the story.
The concept has its downside. Teachers note that making the videos and coming up with project activities to fill class time is a lot of extra work up front, while some detractors believe it smacks of teachers abandoning their primary responsibility of instructing.
"They're expecting kids to do the learning outside the classroom. There's not a lot of evidence this works," said Leonie Haimson, executive director of Class Size Matters, a New York City-based parent advocacy group. "What works is reasonably sized classes with a lot of debate, interaction and discussion."
Others question whether flipped learning would work as well with low achieving students, who may not be as motivated to watch lessons on their own, but said it was overall a positive model.
"It's forcing the notion of guided practice," said Cynthia Desrochers, director of the Center for Excellence in Learning and Teaching at California State University-Northridge. "Students can get the easy stuff on their own, but the hard stuff should be under the watchful eye of a teacher."
At Michigan's Clintondale High School, some teachers show the video at the beginning of class to ensure all kids watch it and that home access is not an issue.
In Kirch's pre-calculus class, students said they liked the concept.
"You're not falling asleep in class, "said senior Monica Resendiz said. "You're constantly working."
Explaining to adults that homework was watching videos was a little harder, though.
"My grandma thought I was using it as an excuse to mess around on the Internet," Nguyen said.