On Easter Monday, when Montgomery County opened schools to make up for a snow day closing, many students didn’t make it to classes.

Nearly 20 percent of students were absent that day, schools officials said. In Maryland’s largest district, with 151,000 students, that means more than 30,000 seats were empty.

The Monday holiday, April 21, had been a long-expected day off. But that changed in early April, after the snow-filled winter brought 10 school closings and Montgomery officials scrambled to compensate for lost instructional time.

Montgomery had four emergency weather days built into its calendar and added one day — Friday, June 13 — to the end of the school year. It then asked the state to waive five days of instructional time, but state officials rejected that request.

So, Montgomery developed a new plan: It asked the state to waive four instructional days and said it would open schools for Easter Monday. The state gave the go-ahead.

Student absenteeism on April 21 registered 19.9 percent.

“We anticipated higher-than-normal absences,” said Montgomery schools spokesman Dana Tofig. “We didn’t have a lot of options before us to make up the day, so we held school.”

The absentee rate for teachers was about 15.5 percent, with a larger-than-usual share of employees taking personal leave, district officials said. The typical rate is 4 to 7 percent, similar to the rate for students.

School officials pointed out that the student absentee rate for April 24, Take Our Daughters and Sons to Work Day, was 19.5 percent, nearly as high as Easter Monday.

For those who did make it to school that day, there were some questions about how much instruction went on.

Parent Carol Liu said her seventh-grader watched four movies at Tilden Middle School in Rockville. She said three appeared related to classroom topics. The other was “Rio,” an animated ad­ven­ture story.

“There seemed to be an effort on the teachers’ part not to have anything too important happen because they knew kids wouldn’t be there,” Liu said.

Liu said that given the state’s request for more instructional time, she found it disappointing “there was not more effort to adhere to the state’s message.”

Montgomery officials said they asked schools not to give tests Easter Monday but to plan for “as close to a normal day of instruction as you can.” Montgomery officials told parents that if they already had made travel plans for April 21, and if those plans could not be changed, student absences would be excused. The state requires school systems to have a minimum of 180 days of class. But with the severe winter weather, most Maryland schools were closed for 10 to 13 days and sought waivers. The state rejected some of those initial requests, saying that school systems didn’t do enough to make up for lost time.