First lady's 'Let's Move' tour to stop in Chicago

First lady Michelle Obama will stop in Chicago this week to promote physical activity in schools.

Obama's Thursday appearance is part of a national tour to celebrate the third anniversary of her “Let's Move” initiative.

In a press release, the White House says Obama will be joined by top officials and athletes and a surprise musical guest. Among those expected are Olympic gymnasts Gabby Douglas and Dominique Dawes, San Francisco 49ers quarterback Colin Kaepernick and tennis player Serena Williams.

The White House says research shows physical activity can improve classroom behavior, attendance and test scores. But only nine states require recess in elementary schools and only 4 percent of elementary schools, 8 percent of middle schools and 2 percent of high schools offer daily physical education.