The ABCs of returning to school

Literacy support teacher Kimberly Clark uses flash cards to teach student Dylson Marte, 6, at Mastery Cramer Hill Elementary in Camden, which brought K-2 students back to school in late February. To ready its 24 schools in Philadelphia and Camden — many of which are in Philadelphia School District-owned buildings — Mastery Schools spent more than $3 million on ventilation and $2.5 million on other safety features.