"Our mission is to provide a free, world‑class education for anyone, anywhere." Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. —Source: Khan Academy website.
Khan Academy has created playlists for every discipline. You can share an individual video or an entire playlist with your students.