VENTURA — This winter, Ventura Charter School’s third-grade class released 75 endangered rainbow trout into the lake at Rancho Simi Valley Park, concluding their investigation into California’s watersheds. The classroom expedition was part of “Trout in the Classroom,” a program in partnership with the California Department of Fish and Wildlife. Students worked on the watershed expedition beginning in August, with a holistic curriculum spanning independent research and activism related to California’s water and wildlife led by teachers Emily Noel and Lindsay Murray and culminating in the release of the fish on Dec. 20.