On a friendly stretch of brownstone sidewalk, monsters and neighbors teach small children their letters, numbers and how to share. Big Bird, Elmo, Cookie Monster, Bert and Ernie, Oscar in his trash can and Grover carry lessons inside jokes, songs and short cartoons, so learning feels like play. Jim Henson's Muppets share the block with a warm human cast. Since 1969 the show has folded real feelings, kindness, loss, curiosity, into a format a preschooler can follow. It grew up alongside public television and stayed gentle, silly and quietly radical about who gets to belong.