Here are some options: Adler Planetarium & Astronomy Museum; The Art Institute of Chicago (free admission for children under 12); Chicago Children's Museum at Navy Pier; Museum of Science & Industry; the Notebaert Nature Museum; Shedd Aquarium; and "Sue" and the "Underground Adventure" at the Field Museum. For more ideas, check the attraction listings on this page, as well as Away.com's Chicago destination overview.

I took 16 Girl Scouts ages 9-12 for 3 days, and they loved the Museum of Science and Industry, and the Shedd Aquarium. Check different museums for their free days. They loved Ed Debevic's for dinner and Rock and Roll McDonald's.