2001. GEMS. The "crime" is a mysterious environmental calamity-a fish die-off that began five years ago. The scene of the crime is the "Gray Area", a watershed that includes forests, a city, a town, a coast, three rivers, a lake, and a pond. Student sleuths are challenged to finger the culprit in this series of investigative classroom activities. This substantial unit conveys solid scientific content and research-related inquiry skills, while placing science learning in a real-world context. 255 pages, soft cover, b&w photographs. Grades 5-8.