As classes resume in sweltering heat, many schools lack air conditioning

Protesters hold up signs outside of the Denver Public Schools administration building to demand equity for students attending classes in excessively hot classrooms. (Helen H. Richardson/The Denver Post via Getty Images)

Eric Hitchner teaches English on the fourth floor of a 111-year-old high school in Philadelphia. Come September, his classroom will be packed with a new crop of teenagers, but one thing will be the same: the lack of air conditioning.

It can get so hot in his room, he says, "no one wants to even move, let alone do some strenuous thinking."