Heather Hartz is a sun-bronzed 21-year-old who loves hanging out at the beach with her friends. But this summer the Florida State University student is teaching in the Chicago public schools, working with some of the city's most academically challenged pupils. "This is a great thing to put on my resume," she said enthusiastically before her first day in the classroom. "It's only going to make me a better person." Hartz and 146 other young adults are part of a six-week summer program, just out of its pilot phase, that is one of the Chicago Public Schools' efforts to lure...