Actress Reese Witherspoon is jumping on the Hollywood charity train...in New Orleans, Louisiana that is. She surprised children at a school by showing up to volunteer as a teacher for the day.

The Academy Award winner visited the Children's Defense Fund Freedom School in New Orleans, where local troubled and at-risk kids learn to become community leaders. The visit was filmed for the upcoming 'American Idol' charity television special called 'Idol Gives Back.'

Witherspoon, former wife of Ryan Phillippe, read a book to the classroom and helped the students to study. She has worked with the charity for several years and regularly participates in fundraising events including donating all of the proceeds from the "Legally Blonde" Barbie dolls.

Other stars taking part in 'Idol Gives Back' include: Brad Pitt, Bono, Miley Cyrus, Mariah Carey, John Legend, Snoop Dog, Chris Daughtry and Carrie Underwood. The special is scheduled to air on April 9 on FOX.