Earning the CFI rating is unlike obtaining any rating a pilot already has. Until going after the CFI, a pilot has faced a maneuver and checkride completion standard of “demonstrating satisfactory knowledge of a task or flight operation.” Suddenly, you, the applicant, are going to have to demonstrate what the FAA refers to as “instructional knowledge” of that task or flight operation—you’re going to have to know the why and how, not just have enough understanding to get by.
What does that mean? Putting it simply, you’re going to have to know all of the material required for a private and commercial rating and be able to explain it clearly as we’ll as be able to demonstrate the ability to modify your teaching method to meet the learning method of an individual student.