brainlyBrainly founder Michal Borkowski.Brainly

One of the things Michal Borkowski is most proud of is that his startup, Brainly, has created a place on the internet where being smart is cool.

Brainly is a bit like Quora for students, a social network where children and teens come to help one another work through homework problems that are stumping them. "Peer-to-peer learning" is how the company describes it.

Students earn points for the quality of their answers and can eventually climb into the leaderboards for subjects like math, biology, and so on.

"On Brainly, when you show you have knowledge, you are cool," Borkowski tells Business Insider. And the network even has its own stars, though not to the extent of places like Instagram.

When Brainly started in Poland in 2009, the goal was simple: Bring the fun and useful elements of study groups to the internet. The startup has since grown to 60 million users, 81% of whom (48.6 million) are active on a monthly basis. Borkowski says one of the keys to the success of the platform is that its users give back to the platform and don't just take from it. About half of students who come in asking a question stick around to answer one later.

Now Brainly is trying to supercharge its growth in the US, where Borkowski will say only that it has "millions" of users. It is raising $15 million in a Series B funding round led by Naspers that brings its total funding to $27 million. Borkowski says investors were most impressed by Brainly's traction in new markets, like the US, and the company's ability to easily scale the platform.

Screenshot at maj 10 10 12 11Brainly

Another goal of the fund-raising is to build advanced personalization into the network. Brainly wants to use machine-learning algorithms to predict what students are likely to struggle with based on the questions they have asked. Brainly could then preemptively connect them with students who might be able to help.

And what subjects do students need the most help on?

Not surprisingly, Borkowski says it's math. Brainly spans 35 countries, and Borkowski says that when the company enters a new market, it sees about 60% of the activity around math. But after about two years in a country, that drops to about 25% — still the biggest category but not overwhelmingly so.

Students come for math help, Borkowski says, but then start to use the service for a variety of subjects.