D.C. law requires schools to track attendance and get involved when children rack up unexcused absences. But schools are also paying closer attention to students who send in doctors notes or accumulate other excused absences.

The District is monitoring “in-seat attendance” — a measure that shows how many kids are actually present on any given day. It helps D.C. Public Schools and the D.C. charter school board figure out which schools have the biggest attendance challenges overall, and also flags days or weeks when attendance falls off.

It’s part of an overall effort to improve attendance in the city’s schools. More than 13,000 public school students in D.C. were chronically truant, meaning they had racked up 10 or more unexcused absences. Thousands more had multiple excused absences.

When it comes to reporting data, Scott Pearson, the charter board’s executive director, said focusing on truancy alone can backfire. It encourages schools to relax policies and accept almost any excuse as valid, he said.

“We spend a lot of time talking about in-seat attendance, what percent of kids are at school, period,” Pearson said. “If you are not in school, you are not in a learning environment.”

DCPS in recent years has shifted away from measuring “average-daily attendance” which counts students with excused absences as attending on any given day, according to Hedy Chang, director of Attendance Works, a national organization that has worked with DCPS. The new “in-seat attendance” measure only counts students who are actually there, which is a more meaningful number, she said.

Chang said children in kindergarten and first grade tend to miss more school with excused absences, because they get sick more frequently or have transportation issues or because their parents don’t think it’s problematic to miss school in the early grades.

But chronic absence early on can set a pattern for later school attendance problems that take away from valuable instructional time, she said.

D.C. schools are seeing some improvement in this measure.

DCPS reported Wednesday its average in-seat attendance rate rose from 86.4 percent in the 2012-2013 school year to 88.5 percent last year. It has not yet released school-by-school results.

The D.C. Public Charter School Board reported last week a nearly 1 percent increase in in-seat attendance — from 90.7 percent in 2012-2013 to 91.5 percent last year.

Some of the charter schools with highest in-seat attendance last year included Washington Latin and Washington Yu Ying with 97 percent each, and Basis DC with 96 percent.

Some of those with the lowest rates included Booker T. Washington, which has since closed, with 67 percent, as well as Options with 75 percent and Maya Angelou - Evans High School with 76 percent.