When you hear about a tech startup that has grossed $5,000,000 in sales, operates internationally, and connects people with common interests, you might imagine a new virtual game or social network. TeachersPayTeachers is neither of those things. Instead, it is a marketplace for teachers to sell their lesson plans to other teachers, and make a tidy profit off of their work.

Why is TeachersPayTeachers so successful? Because it addresses one of the big problems with education in the United States. Often, teachers will need to stay up hours into the night working on the activities for the next day, improving lesson plans and grading papers. This happens night after night, which turns teaching into a grueling process of nightly routine. At the same time, after years of teaching, teachers start to accumulate stacks of activities and daily lesson plans that benefit no one.

This is where TeachersPayTeachers (TpT) comes in. It operates as an online marketplace for teachers to sell their lesson plans to other teachers. This may seem like a small thing, but the growth and sales have been nothing short of phenomenal for such a small market. Founder Paul Edelman shared one remarkable example with me. Deanna Jump, a kindergarten teacher from Georgia is set to hit $500,000 in sales next week (which isn’t pocket change for a teacher). Deanna isn’t alone, either. In fact, four other teachers have passed the $100,000 mark, and dozens have passed the $30,000 dollar mark.

The business is set up to give the majority of the sales to the teachers, while TpT takes its cut from being the middleman. If a teacher decides to become a basic member, they agree to take only 65% of their sales, with TpT keeping the rest. The second option, which is more agreeable to large sellers like Deanna, is to pay TpT $59.95 annually, and they then are allowed to keep 85% of their gross sales. This enables teachers to make a sizable  secondary income, while also keeping TpT profitable.

Not all teachers end up making six-figures from the site, but as a teacher – one of the more consistently underpaid professions – even earning a few hundred extra dollars a month is something to be excited about. As Edelman told me, not only do teachers earn that extra money, but they are also connected through the site to other teachers using their lesson plans. This means that they are hearing stories about their lessons plans being used in classrooms around the country, which is gratifying in and of itself.

While the individual success stories are notable enough on their own, the path Edelman has taken the company on is also impressive. The site was founded in March of 2006, and was sold to Scholastic in December of the same year. During the recession, the site experienced slower growth than Scholastic would have liked, and so he offered to buy the site back. Scholastic agreed, and in March of 2009 Paul once again took control of the site.

Since then, the site has grown 300% annually. There are now over 515,000 registered members, with 30,000 joining every month. Of these, 10,000 are what Edelman described as “active sellers”. These numbers are all made possible by a small team operating around the world – Edelman is in France, the CTO is in America, some are in Ukraine, others in India, programmers scattered around – communicating through Skype, email, phone and SMS. Unorthodox, for sure, but it is certainly a recipe that is working.

With most of the growth occurring in the last 18 months, it is clear TeachersPayTeachers is a prime target for funding at very favorable terms. However, Edelman made it clear that after his experiences with Scholastic, he is hesitant to accept funding. Instead, he is working on growing the site organically, unless funding becomes necessary to accelerate growth.

The most heartwarming part of the entire business is how it benefits everyone involved. Teachers are able to make some extra money, other teachers are given access to top-rated lesson plans, and students get the educational benefits from the best lessons available.