Provides guidelines on weeding science collections in junior high/high school libraries. Highlights include checking copyright dates, online sources, 13 science subject areas that deserve special consideration (plate tectonics, fission, fusion, radioactive dating, weather/climate, astronomy/space science, elements, integrated science, classification, cells, DNA, primates/evolution, endangered species), and a list of the top 10 science selections for grades 6-12. (LRW)