For whatever reason, in this day and age we have this ever increasing trend of teachers trying to create their own classroom materials and whatnot, and myself is no exception. For too long now have I been trapped in this very swirling vortex. But then it dawned on me – why should I have to reinvent the wheel when I the real deal right at my fingertips? I'm sure the same is true for many teachers – they think they know better; they don't want to resort to a third-party material and think that their students need a personalized approach of sorts. Well, let me tell you – the professionals have taken care of all this. A textbook created by a credible institution like Cambridge University is subject to years of research, trial, and editing. What makes you think you are better than them? My suggestion is that you actually take the time to study the program of a given textbook well enough to teach effectively – much too often teachers barely flip through their material. Read the teacher's book (if one is available), watch teacher trainer sessions, and etc. Here is a recommended textbook for Pre-IELTS: Complete IELTS 4-5

Do your due dilligence; see what works for you first and go all in.