Buildings with outdated ventilation systems and racial disparity in school enrollment were among the subjects Secretary of Education Dr. Miguel A. Cardona covered in a school-reopening memo he sent to Ron Klain, the White House chief of staff.

“I saw firsthand during my tour how difficult the school year has been for students, parents, teachers, and school staff,” Cardona wrote. “Whether the school had just recently transitioned into a hybrid model or been fully open for months, the work has been challenging for all.”

CNN, which obtained a copy of the memo, has more.