I enjoyed taking the 120-hour course offered by World TESOL Academy.
The cost is low, but the value is high, the material is a wealth of information. The course covers many things, like the basics of sentence structure, tenses, punctuation, and much more! It also has a lot of resources on teaching online, intrinsic/extrinsic motivations of students, and how to motivate them, putting together lesson plans, dealing with disciplinary issues.
The course took me roughly 3 weeks to complete, wo...