By Chris Morris

PHILADELPHIA (CBS) – On today’s APP-tastic and outta SITE – Khan Academy.

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Maybe you didn’t pay close attention in school but now wish you had. Khan Academy is an online learning app that lets you learn about everything from math to art history – for free.

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There are over 5,000 videos to choose from, which can even be downloaded and watched offline. And it can be a good tool if you’re boning up for a standardized test.

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Check out the Khan Academy app.