School’s back in session in the art world, too — this fall, exhibitions on textbook artists like Abstract Expressionists Lee Krasner and Jackson Pollock, Pop artist Roy Lichtenstein, and modernist Constantin Brancusi are landing at The Met, the Whitney, and MoMA, respectively. Then there’s the shows writing the textbooks of tomorrow: surveys of artist-filmmaker Arthur Jafa, who remixes and shapes Black visual culture; photographer Taryn Simon, w…