This batch of the week's best iPad apps is all about learning. Whether it's U.S. presidents, or human anatomy, you're beefing up your brain muscle.

America's Presidents: The Smithsonian National Portrait Gallery combines art, history, and one of my personal favorite topics—U.S. presidents. Learn all about our 43 commanders-in-chief, and see their iconic pictures, which hang in the DC museum. $5

Essential Anatomy: Here's a great way to use the iPad's retina display—look at human anatomy in 3D. In this iPad app, you can view all 6 systems of the body in intense details. $30

Sound Uncovered: Why does the sound of a car door make you want to buy one vehicle over another? This app—new from the San Francisco Exploritorium—lets you play with sound in a very unconventional, game-like way, in order to understand the every day noises around us. Free