Though the Barnes Foundation doors are temporarily shut, this interactive online platform allows you to sample its treasures from home. Online classes explore the hidden truths in works by Cézanne, Matisse, and Seurat, and analyze groundbreaking movements in art. There are also private virtual tours led by a docent, as well as Instagram live talks, weekly YouTube videos with curators and scholars, and a new online series, “Facing Change,” that discusses race-related issues with scholars, artists and activists. —E.C.