ABC News' Sunlen Miller Reports: Barack Obama dropped his two daughters off at school Monday -- in a motorcade complete with a Secret Service detail -- for their first day back to school in Chicago. The Democratic nominee, dressed in work out clothes and a baseball hat, held the hands of his daughters, Malia, 10, and Sasha, seven, as they walked, toting backpacks, into the University of Chicago Laboratory School.The elite charter school costs between $15,000 to $20,000 a year in tuition. Michelle Obama currently sits on the board.Obama's eldest daughter, Malia, is going into 5th grade, and his youngest is going into the 2nd grade. If Obama wins the White House, his daughters would be the youngest kids in the White House since President Jimmy Carter's daughter, Amy. After dropping his kids off at school, Obama hit the gym and then flew off to Michigan for a day of campaigning."My kids started school today," Obama told the Flint crowd. "Took my 5th grader and my 2nd grader to class. The 5th grader didn't really want me to go up to the classroom but I went. She's still Daddy's girl."