Hello donay, thank you a lot for answering my question.
Actually, I've been thinking about starting teaching English as a second activity. But I've known only the traditional and slow methods.
So, when my brother told me about Callan, I also found it very interesting and got curious.
My brother is a beginner and he's made another stop in the course. He's the type that learns English by fits and starts.
I'd like to find someone who has tried the method either as a student or teacher so that I can make a clearer idea on it. This method hasn't been taught in the schools where I live.