Thousands of Chicago school children and teachers will help the first lady celebrate the third anniversary of her anti-obesity program called “Let’s Move.”

The White House is promising a big announcement from Mrs. Obama and the CEO of Nike about a new program to increase physical activity in schools.

The private event will be held Thursday at McCormick Place.

There will be a surprise musical guest, plus tennis star Serena Williams and Olympic gold medalist and Indiana native Gabby Douglas.