Michelle Obama kicks off book tour at United Center

CHICAGO — Former First Lady Michelle Obama's new memoir, "Becoming," arrived on shelves Tuesday, and the former first lady launched her book tour in Chicago.

"Becoming" chronicles her childhood on the city's South Side through to her eight years at the White House.

Obama signed copies of her book at the Seminary Co-op Bookstore in Chicago's Hyde Park neighborhood Tuesday ahead of her appearance at the United Center. The book signing event sold out quickly.

A group of students was surprised when they were told they were going to be guests at Obama's book launch event. They said they had no idea where they were going when they got on their bus.

The 31 students were from northwest Indiana and part of an entrepreneur foundation named Ecier. They boarded a bus in Hammond, but only a few people knew where they were headed.

The former first lady was interviewed by Oprah at the United Center.