StudyPool, a 500 Startups batch company that connects students and tutors, is yet another company that takes the template for building a marketplace from Uber and Airbnb and applies it to another area where there’s usually a lot of friction involved in each transaction.

StudyPool co-founders Richard Werbe and Jimmy Zhong have built their startup around some of the key lessons from other successful marketplace services — specifically, working to bolster both the demand and supply sides of transactions.

For instance, there’s no landing page hyping the service before you get to see what it’s actually like — the home page starts with a text box for asking a question you’d like to see answered quickly, then summarizes how the site works, and concludes by showing examples of the kinds of in-depth questions people are willing to pay for answers to. Aesthetically it looks a bit rough (Werbe says it’s the same design the pair launched with back in March) but functionally, StudyPool does a great job of onboarding.

Speaking of the easy questions at the top, StudyPool’s reputation system incentivizes tutors to answer those questions quickly between hunting for questions that people are willing to pay to get help on. When people have questions that are more in-depth or need help putting together a thesis outline, they give a range of prices they’d be willing to pay for assistance.

By answering lots of easy questions, tutors can quickly build up their reputation, making it easier to charge the higher end of people’s price range. People can even request help from specific users, so if you have a great reputation on the site you may find that you start signing in with an inbox full of paying customers waiting for you assistance.

That incentive system has brought the average response time for questions down to just 11 minutes. If a question takes much longer than that to get a response, StudyPool notifies you that the question may be too difficult to answer for free and that you should repost as a paid question.

Right now, Werbe says there are essentially three popular tiers for tutoring pricing: free, $1, and $5. That’s not something StudyPool imposed on its users — rather, those seem to be the dominant market-clearing prices that have emerged naturally.

With such low amounts, you’d think that StudyPool would have trouble bringing in people to actually answer questions students get in college classes. According to Werbe, nearly 18,000 people have signed up to tutor (compared to almost $32,000 who have signed up for assistance) and among that group, there are approximately 500 “super tutors” who answer 20 questions a day or more on average. Within that group, some have answered thousands of questions — making enough that some are even quitting their jobs to provide assistance full-time (the official bragging right of marketplace apps everywhere).

While it’s not something many entrepreneurs brag about in the current high-investment, high-growth startup ecosystem, StudyPool has been profitable from day one thanks to the 20 percent transaction fee the company has been collecting since launch. Now that they’re in 500 Startups, the duo is looking to expand their team. They plan to bring on several engineers in January to build out the company’s tech and expand the ways users can access the service (right now, there’s only the web app).