Small groups place sand and ice in a covered box, place the box in the sunlight, then observe as evaporation, condensation, and precipitation occur. These models serve as miniature water cycles and demonstrations of the three phases of matter that water is found in: solid, liquid, and gas.  If you can afford it, purchase a few plastic shoebox-sized tubs rather than trying to use aluminum-foil-lined cardboard boxes. The foil is certain to leak and soak the cardboard leading you to need to find a new set of boxes each school year, whereas plastic tubs can be reused. This instructional activity is part of a unit that provides tremendous teacher resources!