Khan Academy

Spend an afternoon brushing up on statistics. Discover how the Krebs cycle works. Learn about the fundamentals of music notation. Get a head start on next semester's geometry fundamentals. Prepare for the SAT, GMAT, LSAT, MCAT, or NCLEX-RN. Or, if you're feeling particularly adventurous, learn how fire-stick farming changes the landscape of Australia.

Whether you're a student, teacher, homeschooler, principal, adult returning to the classroom after 20 years, or a friendly alien trying to get a leg up in earthly biology — Khan Academy's learning library is available to you, for free.

- Learn anything, for free: Thousands of interactive exercises, videos, and articles at your fingertips. Study math, science, economics, finance, grammar, history, government, politics, and much, much more.

- Sharpen your skills: Practice exercises, quizzes, and tests with instant feedback and step-by-step hints. Follow along with what you're learning in school, or practice at your own pace.

- Keep learning when you're offline: Bookmark and download your favorite content to watch videos without an internet connection.

- Pick up where you left off: Your learning syncs with khanacademy.org, so your progress is always up-to-date.

Learn using videos, interactive exercises, and in-depth articles in math (arithmetic, pre-algebra, algebra, geometry, trigonometry, statistics, calculus, linear algebra) science (biology, chemistry, physics), economics, humanities (art history, civics, finance), and more!

(For our Indian learners, we have aligned math and science content in our app to NCERT/CBSE curriculum. Study more effectively for your 6-to-12-grade math classes with our quizzes and tests. You'll also build a strong foundation for your boards, CAT, GMAT, IIT-JEE, and other exams.)

Khan Academy is a 501(c)(3) nonprofit organization, with the mission of providing a free, world-class education for anyone, anywhere.