Arlene Harper has dealt with big change before. In fourth grade, she came to the first day of school in new leg braces. But the changes that rock her world this year feel like a total earthquake. Inspired by a social studies unit on our country's biggest social movements, and perhaps prompted by the cafeteria's overflowing garbage cans, Arlene and her friends launch a campaign to reduce their school's carbon footprint. Like most rebellions,...