Back in 2008, Open English, a company run from Miami that uses online courses to teach English in Latin America, had just a handful of students in Venezuela and three employees. Today the company has more than 50,000 students in 22 Latin American countries and some 2,000 employees.

To fund this meteoric expansion, the founders of Open English — Venezuelans Andrés Moreno and Wilmer Sarmiento and Moreno’s American wife, Nicolette — began with $700. Over the last six years, the partners have raised more than $55 million, mostly from private investment and venture capital firms.

Their formula for success? The founders rejected traditional English teaching methods in physical classrooms and developed a system that allows students to tune into live classes every hour of the day from their computers at home, in the office or at school, and learn from native English-speaking teachers who may be based anywhere. Courses stress practical conversations online and the company guarantees fluency after a one-year course, offering six additional months free if students fail to become fluent.

“We wanted to change the way people learn English,” said Andrés Moreno, the 30-year-old co-founder and CEO, who halted his training as a mechanical engineer and worked full-time at developing the company with his partners. “And we want students to achieve fluency. Traditionally, students have to drive to an English academy, waste time in traffic, and try to learn from a teacher who is not an native English speaker in a class with 20 students.”

Using the Internet, Open English offers classes usually with two or three students and a teacher, interactive videos, other learning aids and personal attention from coaches who phone students regularly to see how they are progressing.

Courses cost an average of $750 per year and students can opt for monthly payments. This is about one-fifth to one-third of what traditional schools charge for small classes or individual instructors, Andrés noted.

“We work at building confidence with our students and encourage them to practice speaking English as much as possible during classes,” said Nicolette Moreno, co-founder and chief product officer, who met Andrés in Venezuela while she was working there on a service project. “Students are taught to actively participate in conversations like a job interview, traveling and talking on a conference call,” said Nicolette, who previously lived in Los Angles, worked with non-profits to create environmentally friendly products and fight poverty in emerging markets, and was head equity trader at an asset management firm. “Students need to speak English in our classes, even though it is sometimes difficult. They learn through immersion.”

Open English has successfully tapped into an enormous, underserved market. Millions of people in Latin America want to learn English to advance in their jobs, work at multinational companies, travel or work overseas and understand the popular music, movies and TV shows they constantly hear in English. Many of them take English courses at public and private schools and learn little if any useful conversational English. While students at private schools for the upper middle class and wealthy often learn foreign languages extremely well from native English-speaking teachers, most people can’t afford these schools or courses designed for one or two students.