This startup has built a community of about 50 million monthly users where 'being smart is cool,' and it just raised $15 million

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 each other 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 a simple one: to bring the fun and useful elements of study groups to the internet. The startup has since grown to 60 million users, 81% of which (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: around half of students who come in asking a question stick around to answer one themselves.

Now Brainly is trying to supercharge its growth in the US (where Borkowski will only say it has "millions" of users), and has raised $15 million in Series B funding led by Naspers, bringing 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.

Another goal of the raise is to build advanced personalization into the network. Brainly wants to use machine learning algorithms to predict what a student will likely struggle with in the future, based on the questions he or she has asked in the past. Brainly could then preemptively make sure they connect with students who might be able to help them.

And what subjects do students need the most help on?

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

Students come for math help, but realize that Brainly can be a useful tool for a variety of subjects, Borkowski says.