Ever wondered how Agnes Martin balanced perfection and imperfection in her gridded compositions, why Jackson Pollock was dubbed “Jack the Dripper,” how Mark Rothko sought to make viewers cry, or what a Willem de Kooning painting sounds like? Sign up for “In the Studio: Postwar Abstract Painting,” MoMA’s newest free online course—now open for enrollment at mo.ma/coursera. This course welcomes anyone to tap into the processes, materials, and minds of seven New York School artists including Martin,