From your experience, what is the more factor to gain the customer satisfaction in a training program ?

Thanks for the invitation

They are not customers >>>They are trainees

The most important factor in training session, from my point of view, is "participation" or keeping the trainees involved within training

Even though the trainees are participants in the training program, I like to look at them as my customers which will drive me to excel and do a superb job conducting a successful training program for them. And as Mr. Mohammed mentioned, it's all about participation by using adult learning technologies.