The St. Louis Science Center
Click here to visit the St. Louis Science Center website.
This museum is packed with hands-on exhibits and their website is full of information and resources. It is a great "down-state" alternative to the Museum of Science and Industry. There are a number of workshops available to Teachers as well. Their w ebsite is very dynamic and changes often so check there for the latest information.
Of special interest to those who teach astronomy, they offer a workshop covering the use of their portable planetarium and participants may check it our for two days as part of their registration fee.