I thought I'd better start another post for this. Now I'm not speaking from first and knowledge, but second hand. My boss whose a PT, got her PT certification first, then went for the primary cert. She did not teach any classes before that time. So I'm assuming that she had to have a cert. of some kind that allowed her to teach in a class setting. I'm wanting my PT but I must wait for the money{I'm ALWAYS waiting on having enough money!!}I'm hoping before next summer. Anyway, you were right about Cathe's videos helping me!! Especially MIS and BodyMax!! My boss takes my class and after I got Cathe's tapes and did some things different{like Cathe} she told me my class was killer!! Thank You Cathe!! I was surprised to find that the MIS tape was extremely close to my own class format!! I even involve a step in my classes! Some things were different and the ones I really loved I add to my very next class!! I start with the major muscle groups first, then smaller groups, then abs & lower back, then cooldown and stretch. If you are ever going to be in the Delaware,OH area, let me know and I'll take you to one of my classes!!!