BOULDER, Colo. (KDVR) — An in-depth study of the comings and goings of kindergarteners at an urban school district found that 5- and 6-year-olds spent a lot of time doing nothing between activities in schools serving lower-income communities, compared to their wealthier counterparts.

University of Colorado Boulder Education Professor Mimi Engel was the lead author of the study that included researchers from the University of Michigan and University of Wisconsin-Madison.

Over the course of three years, researchers focused on one urban school district, spending 82 days observing 32 classrooms. Of those classrooms, 24 were in communities where on average 90% of students qualified for free or reduced-price lunch. In the other eight classrooms, only 15% of students on average met that threshold.

“We don’t know what the ideal kindergarten day should looks like for kids,” Engel said in a release about the study. “This is our first attempt to explore the kindergarten experience for kids in an urban setting.”

Engel and her fellow researchers observed that students at the lower-income schools wasted away 42% of their day (2.5 hours of a 6-hour school day) transitioning between activities.

Students in the higher-income communities wasted about 33% of their day during these transitions, or roughly two hours, according to Engel’s research.

Engel theorizes the gap in time wasted may come down to staffing, that more adults were available in the schools serving higher-income communities.

“This is troubling. When I have the opportunity to spend time in schools, something I think about is: ‘Would I want this for my own kids?'” Engel said in the release. “And when I think about what I observed in kindergarten classrooms serving kids from low-income households, my answer is ‘no.'”

You can read the full study here.