Beginning in the early 1980s, a lot of states began to open up the pathways to becoming a teacher. People who already had a bachelor’s degree in something else didn’t need to go back to college to get trained in teaching. Policymakers hoped this would solve teacher shortages by getting more people into the profession, but it’s also opened up a whole new business model in educator preparation: Online for-profit teacher training programs have proliferated, and they’re growing fast. One program in Texas has become the single largest educator preparation program in the United States by enrollment, and it’s expanding into other states.

Learn more: Who wants to be a teacher?