Their learning system is mastery-based, which allows students to master key concepts at a pace that’s just right for them before moving on to more challenging content. Khan Academy’s platform is free for students and teachersand includes thousands of interactive exercises, videos, and articles that cover a range of K–12 subjects. They offer free personalized SAT practice in partnership with the College Board, MAP Accelerator in partnership with NWEA, Khan Academy Districts, Official Praxis Core Prep in collaboration with ETS, and Official LSAT Prep in collaboration with the Law School Admission Council. More than 18 million learners use Khan Academy every month in 190 countries and more than 40 languages. More than 200,000 educators use their free teacher tools. As a nonprofit, Khan Academy relies on donations from foundations, corporations, and individuals around the world, as well as earned revenue.