The Eisenhower National Clearinghouse for Mathematics and Science Education (ENC) helps teachers by offering a broad assortment of services to enable them to quickly locate educational resources. This document is one in a series of print catalogs designed to give educators information about curriculum resources available for teaching math and science in K-12 classrooms. Each issue of ENC Focus presents a selection of the Clearinghouse collection focused on a topic of particular interest to math and science teachers. In addition to meeting general requirements for inclusion in the ENC collection, curriculum materials in the Focus series are appropriate to the specific topic of the issue; support hands-on, active, inquiry-based methods of instruction; and are readily available. This issue offers a sampling of useful informal educational materials and other resources in mathematics and science education. A one-page description of each resource provides an abstract of the contents, subjects addressed, grade level, publication date, ordering information including price, authors, and related resources. (ASK)