A group of American college students stands in a semicircle, clapping and hopping on one foot as they sing in Yiddish: “Az der rebe tantst, tantsn ale khsidim!” In English, the lyrics mean: “When the rebbe dances, so do all the Hasidim.”. This isn’t music appreciation or even a class at a synagogue. It’s the first semester of Yiddish at Emory University in Atlanta — one of just a handful of college programs across the country studying the language.