Developer: Salman Khan

Rating: 4.6

Khan Academy is a free app that is great for school. You can prepare for the SAT, GMAT, LSAT, MCAT, or NCLEX RN. You can study math, science, economics, finance, grammar, history, government, politics, and more. You can sharpen your skills by doing practice exercises, taking quizzes, and tests. Each method provides instant feedback and step-by-step hints, so you can correct what you have previously gotten wrong. Another bonus to Khan Academy is – you can always keep up to date with your current school classes and assignments. Download Khan Academy… for free!