HVAC projects to improve indoor air quality. Tutoring programs for struggling students. Tuition support for young people who want to become teachers in their home communities.

These were some of the ways Maryland schools were using what remained of the state’s federal pandemic relief dollars.

Those projects and similar ones in schools around the country are now on hold — and states and school districts are on the hook for hundreds of millions of dollars — after Education Secretary Linda McMahon said the U.S. Department of Education would not pay for any more expenses related to pandemic recovery.

In a letter to state education leaders Friday, McMahon said the department would not honor deadline extensions to spend COVID aid it had approved just a few months ago under the Biden administration.