Khan Academy offers more than 2,700 instructional videos covering math, science, finance, and history. These short but informative videos have become a worldwide teaching and learning phenomenon. Created by experts, Khan Academy’s library of trusted, standards-aligned practice and lessons covers math K-12 through early college, grammar, science, history, AP®, SAT®, and more. It’s all free for learners and teachers. Students practice at their own pace, first filling in gaps in their understanding and then accelerating their learning.