During the summer, the normally bustling Boston University campus quiets down. The crowded streets of Commonwealth Avenue aren’t nearly as crammed, and the atmosphere is more relaxed. But over the course of Labor Day weekend, campus has sprung back to life. With students returning from break, campus is jammed with moving carts and new freshman checking the campus maps every several minutes. New changes around campus like new Terrier Cards, 100 Bay State Road, and the new Pedestrian Malls are going to take some getting used to as students prepare for the 2012-2013 school year.