Children playing in damp sand invariably try to make a tower or a tunnel. By providing experiences with a variety of materials, alone and together, teachers set up the conditions for children to learn through their senses and ensure that a class approaches a topic with a common set of experiences to build on. Learning about the properties of materials, trying to solve problems, and communicating about the results are part of the National Science Education Content Standard A: Science as Inquiry and Standard B: Physical Science (NRC 1996).