perhaps borrow some ideas from Odyssey of the Mind spontaneous problems for quick "warm ups" to break the ice, etc. They have "hands-on" and "verbal" problems with a range of requirements. Examples: name things that are red (or read) name things that change, name uses for _____, build a tower out of provided materials that holds pennies, build a transport device, etc.
http://www.geocities.com/nepaootmspon/