The Sierra Club has produced an excellent, brief, overview of the current state of the Dakota Access Pipeline, and the efforts of the Water Protectors to halt its construction.  This may be the best brief summary of the issue I have seen.  You and your students will find this useful in arriving at an understanding of a movement that is both alike and unlike so much of Native American History: A protest movement, utilizing social media and networking to assemble a widespread, grass-roots protest movement, and yet another chapter in the long struggle of native peoples to protect not only their lands, but the land.