Luis Sierra sleeps in a classroom Oct. 13 at a school turned shelter after Hurricane Maria left him and other families homeless in Toa Baja, Puerto Rico. (Ramon Espinosa/AP)

Puerto Rico is slated to open about one-tenth of its schools Tuesday — despite not having electricity in classrooms — a small but critical step in returning one of the nation's largest school systems to normalcy.

The territory's Department of Education said students will return to classes at 119 campuses in the island's capital, San Juan, and in Mayaguez, on the west coast. Students at an additional 26 schools, which are being repaired, will be transferred to nearby schools that are ready to accept students. Teachers returned to schools Monday to prepare their classrooms.

Before Hurricane Maria hit Sept. 20, the island had more than 1,100 schools that educated 347,000 students, nearly all of whom qualified for free meals. Officials expect that many students have left the island and enrolled in schools in Miami, Orlando, New York and other areas with large populations of Puerto Ricans.

Julia Keleher, the education secretary in Puerto Rico, said it remains unclear when the department will be able to reopen the remainder of the schools and said the agency may decide to shutter some permanently.

The Education Department had opened some schools as ­service centers, places where children could take half-day classes and where teachers and families could meet with federal officials. Other schools were being used as shelters, their classrooms transformed into makeshift bedrooms for displaced residents across the island.

Tuesday is the first time any school will host a full day of classes, albeit without electricity, since Maria.

The storm struck a beleaguered school system. In an effort to save $7 million, Keleher closed 179 schools this year as the island grappled with a deepening debt crisis. About 18,000 students left Puerto Rican schools as their families moved away from the island.

She said waiting for the power to return would have kept students out of classrooms for many more weeks. So rather than keeping the schools closed, she is urging teachers to get creative in their instruction. Some schools were accustomed to outages even before the storm.

"We want to try to bring the maximum benefit to the maximum number of students while protecting their safety and well-being," Keleher said.

The Army Corps of Engineers has been assessing school buildings to ensure it is safe for children to return. Keleher said the island's Education Department will reopen schools only after they are deemed safe and found to have clean, running water.

Keleher said she hopes teachers will make the best of the challenging situation and urged educators to abandon outdated teaching methods in favor of more hands-on, "project-based learning," which encourages students to find solutions to real-world problems. She sees it "as a huge opportunity for Puerto Rico and public education to re-engineer itself and for it to become an uplifting learning opportunity."

The education department has begun to rewrite required curriculum. Keleher said she hopes teachers will incorporate the recovery from the storm into their classroom lessons.

Get updates on your area delivered via e-mail