Recent government publications like "Benchmarks for Scientific Literacy" and "Science for all Americans" have given teachers a mandate for improving science education in America. What we know about how learners construct meaning--particularly in the natural sciences--has undergone a virtual revolution in the past 25 years. Teachers, as well as researchers, are now grappling with how to better teach science, as well as how to assess whether students are learning. Assessing Science Understanding is a companion volume to Teaching Science for Understanding, and explores how to assess whether learning has taken place. The book discusses a range of promising new and practical tools for assessment including concept maps, vee diagrams, clinical interviews, problem sets, performance-based assessments, computer-based methods, visual and observational testing, portfolios, explanatory models, and national examinations.