The most important section of a TESOL or TEFL course is Methodology. This is where the trainee learns to create lesson plans. A Practicum module is important, but a teacher cannot effectively meet the needs of their students without having learned how to create lesson plans. For this reason, a Practicum module comes at the end of an on-site or online course.
A TESOL or TEFL course shall also offer throughout training in Grammar and Phonology. Most native-speakers have not received proper training in high school or university. They can speak the language, but they cannot teach it unless they know the rules of the English language.