One way to organize center activities (and to conserve space) is to combine all of the necessary materials for a particular activity into a resealable plastic bag. Have the bag hanging from a plastic chain (can be found at a hardware or baby store) using a clothespin. This works especially well for centers that provide choices for the students. For example at the Science center: one baggie might have leaves, bark, grass, and pine needles along with instructions for creating crayon rubbings; another baggie could contain food coloring, a stirrer, and observation sheet.