The interview was a phone call followed by a mock class to teach another teacher a example class topic. The teacher would make some mistakes on purpose for you to catch and correct them

I had a phone screening interview and then a "reverse teaching" session a week later where I gave a mock lesson to one of the instructors. They provide the lesson materials and an environment to practice your solution and experiment with the source code. The screening interview was mostly standard questions and both interviewers were very nice!