to the forums, Mohammed.
There are hundreds of textbooks on this subject.
To make it simple, let's choose three ways people (generally) learn:
Visual learners learn primarily by seeing and looking.
Aural learners prefer to learn by hearing and listening.
Kinesthetic learners learn best by physically doing something.
In your group of 30 trainees, I am sure that there are any number of the three types. Assuming that, there is not one way to train.
General rules and regulations (policies), are by design geared to visual and aural learners.
Specific job tasks are best suited to kinesthetic learners.
There is nothing worse (at least IMO), to sit in a classroom and listen to someone read a bunch of Power Point slides without attempting to elaborate on the bullet points on the slide. I can read, therefore there is no reason for me to listen, unless the trainer provides insight or examples to bring the bullet points to life.
I can recite the metal detector test procedure and what to do if it fails. That is fine, but if it's not demonstrated, and then actually done, by the trainee, my recitation of the procedure is of limited value.
Trainers need to understand that trainees learn differently. Trainers need to understand the subject matter, and be able to improvise and demonstrate points if necessary. Do not lecture people. Ask questions. Tell stories. Encourage participation by the trainees.
It really all comes down to the subject matter.
Let's take GMP's as an example. This is not allowed, that is not allowed, you have to do this, you have to do that. OK. Provide an example of what happened when one of those rules was not followed. "We all know that you have to report to your supervisor that a bandage (plaster) you were issued comes up missing. Last week someone didn't report it, and that bandage ended up being detected at one of our metal detectors. Thankfully, it was found. Imagine what would have happened if one of our customers received a complaint because a consumer found a bandage in their hamburger bun?"
Training is not a one size fits all proposition.