Most popular: The Class of 2015s 15 favorite apps

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What keeps teen thumbs in shape? According to the Pew Research Center, 73 percent of teens have smartphones and 92 percent go online daily. To find out which apps and sites they're spending their time in, research firm Niche surveyed 10,000 kids from the high school class of 2015 about what makes them click.

Here are the Class of '15's 15 favorite apps.