Academy Award winner Reese Witherspoon surprised children at a school in New Orleans, Louisiana recently - by becoming a volunteer teacher for a day. The kind-hearted mother-of-two visited the Children's Defense Fund Freedom School, where at-risk kids learn to become community leaders. During her trip, which was filmed for upcoming American Idol charity special Idol Gives Back, Witherspoon helped the children study and at one point read a book to a class of students. The Walk The Line star isn't the only celebrity taking part in the U.S. TV special - Brad Pitt, Bono, John Legend, Snoop Dogg and Carrie Underwood will also feature during the show, which is set to air on 9 April (08).