It is a good idea that the trainer explains why he is using this or that training style or training technique before carrying it out. When participants understand the benefits of a specific activity or training method they start appreciating it and giving it their full attention and resources because they become aware that their efforts will pay back handsomely in terms of personal skills gained.
Sometimes, however, it is advisable to reveal the real reason behind carrying out a specific training activity after it is completed and not before it starts. Such cases are when revealing the real reason behind the activity would spoil the activity and not make participants benefit from it well. At other times it could even be advisable to hide some or all of the real reasons behind carrying out a specific training technique yet the trainer is well aware of the benefits of such technique to participants.
Thus a trainer should have the flexibility and awareness to switch between mentioning the reasons behind a specific training activity before it starts, after it is completed or not at all.
When do you think a trainer should hide the real reasons behind a training activity?