The first kids who learned the letters of the alphabet from Sesame Street could have grandchildren by now—but Big Bird hasn't aged a day. Using TV to educate preschoolers was a radical concept in 1969, when Sesame Street founder Joan Ganz Cooney and Muppet creator Jim Henson launched their "fairly small" children's show. Forty years later, the show is a global phenomenon, watched in 140 countries.
Over the decades, Sesame Street has tackled tough social issues and adapted its characters to local contexts—like Kami, the HIV-positive muppet on South Africa's Takalani Sesame, CBS reports. A show that has hosted stars from Johnny Cash to Jake Gyllenhaal will welcome a new special visitor to its season launch tomorrow: First Lady Michelle Obama, who will plant a garden and promote healthy eating.