The NCTQ report found districts spend an average of $1,800 per teacher to cover absences each year.

New Hampshire social studies teacher Ben Adams said it's rare he's anywhere but his classroom when school is in session because his consistent presence is part of the learning environment he cultivates.

"Attendance for a teacher, it's not curriculum, it's not the star of the show, but it's one of those subtle things that goes a long way to dealing with other parts of teaching — classroom management, trust, risk," the Salem High School teacher said.

Omaha, Nebraska, teacher Maddie Fennell, on the other hand, said her national work around professional development and policy took her out of the classroom 20 to 30 days some years and her students and the others in her building have benefited by posting measurable academic gains.

"When I go out and do this work, I come back and bring the learning with me back to my school," she said, adding that a consistent substitute teacher has helped.

Among the report's other findings, while some districts, including Indianapolis and the District of Columbia, had higher rates of teachers with excellent attendance — three or fewer days absent — and lower rates of chronically absent teachers, that wasn't the rule.

Buffalo Public Schools, for example, had the second-highest rate of excellent attendance (30 percent) of the 40 districts studied but also the highest rate of chronically absent teachers (37 percent) in 2012-13. The district did not respond to requests for comment.

The report also found no measurable relationship between teacher absence and the poverty levels of a school's students, nor any difference in absentee rates among districts with policies meant to encourage attendance, such as paying teachers for unused sick time, and districts without those incentives.