Teaching English as a Second Language is not the easiest job in the world. Most teachers work at more than one school and have private students. Expanding your teaching skills allows you to get more teaching jobs and make more money.
Many ESL students that live in the United States may also want to get a GED. The GED contains an English section. That material is easy to incorporate into your curriculum. The Social Studies component should also be easy to implement. If you like Math (Basic and Pre-Algebra, Algebra, Geometry) that is an extra source of income as well as the Science component. If not, teach the English component and see if you can create a referral program with teachers that are good in math and science but not English.
SAT preparation is another excellent source of income. Like the GED, you can specialize in the English component or teach all sections.
In a previous post, I wrote about how small, local language schools that can’t issue I-20s have limited revenue because their customers are on fixed incomes. Certainly, GED training is an extra source of revenue. SAT preparation can also be an additional source of income. This allows schools to expand their reach in their communities. While the immigrant communities are on fixed incomes, the American-born members may be more flexible with their incomes. The schools can charge more than they would for ESL lessons but less than the Kaplans and Princeton Reviews. It is a win-win opportunity for schools and students.