Since Time Immemorial is a collection of curricular resources about Washington state and U.S. history that center on the history and perspective of tribal communities. These resources were designed by the Washington State's Office of the Superintendent of Public Instruction and the Office of Native Education in collaboration with individual tribes and school districts. These resources include lesson plans for students in elementary, middle, and high school; educational videos; and links to helpful outside resources. While these resources were designed specifically for students in Washington state, some of these resources may be helpful when incorporating tribal perspectives into social studies classrooms across the United States. These lessons plans and resources are aligned with Common Core Standards and are designed to be easily incorporated into existing history and social studies curricula by providing tribal perspectives on topics and themes already addressed in U.S. history and world history classrooms.