By Amy E. Feldman

PHILADELPHIA (CBS) - Think you know what your mobile apps do? You might be surprised.

Researchers at the Carnegie Mellon University Human-Computer Interaction Institute (that’s a fun group of guys) studied 100 Android apps and found that 56 collected location information, device identifiers and/or contact lists and, in many cases, gave the info to marketers.

Not a surprise for a map app, for example, which needs to know your location to give you directions. But you might be surprised that The Brightest Flashlight App also tracks your location and, provided a device ID, same for Shazam Music. And, Pandora Internet Radio tracked your device ID and your contact list. Even Angry Birds app tracks the device ID and location.

Is that legal? Yes, so long as in their user agreement, app makers say what they track and what it may be used for. But when your kid is screaming “I WANT ANGRY BIRDS!” you’re probably not scrolling all the way through those terms of use and really taking the time to figure out what data they’re collecting and what they’re using it for. Instead, you hit “I AGREE!” without the lightbulb of understanding what you just agreed to ever going on.