Did you know that the plain old Cardboard Box was recently inducted into the National Toy Hall of Fame?
Boxes are wonderful, open-ended materials that can be used in all sorts of creative, preschooler-approved ways. It's Not A Box is a fantastic storybook that touches on the brilliance of boxes, and helps gets kidlet imaginations whirling.
One of my favorite uses for boxes is to open the bottoms and then line them up to make "mole hole trails"... kids can arrange them as they please (tape together, if you like), and then crawl through, pretending to be underground critters (moles, gophers... even snakes!) This is an especially fun rainy-day activity (btw: if you have a cat, she'll love it, too... cats love them a cardboard box!)
Writing the post a couple days ago about those vintage space songs reminded me of another fun activity: turning big boxes into space shuttles! Superduperbusymomtypes can even buy box kits, complete with instructions (like the rocket shown above, available @ Simple Family Living.) Kids can then add their own personal touches with paints and things, but I've gotta say I prefer the 100% homemade, fridge box versions best... like the one shown below (visit the Instructables site for inspiration & helpful tips.)