Elaine Schwartz, who in 1982 was a founder of the Center School, a public middle school in Manhattan, as a way to introduce bold classroom innovations, then remained its principal for four decades — long enough to see many of those innovations become common practice in schools nationwide — died on June 24 at her home on the Upper West Side of Manhattan. She was 92.

Many of her once-radical ideas are today the norm in education — students receiving narrative report cards rather than number grades, and being included in parent-teacher conferences rather than having to sit outside expectantly. One of her biggest innovations is its emphasis on theater arts: Every student is required to participate in two schoolwide shows a year. to help preteenagers learn to become comfortable with their bodies. “The confidence they gain is amazing,” she said.