This is a very good discussion.
I think the overall trainer's lesson to take away is that adult (including workplace) education is somewhat different than earlier education. Two basic principles apply:
1) Adult students learn best in small, specific "bites": what they need to know, when they need to know it. Thoughts similar to "I really need to get back to XYZ, I have a deadline" tend to encroach on learning patterns. Relevance is key, hopefully to already-recognized needs. If the need for the knowledge is not yet clear, relevance needs to be established first-thing.
2) Capabilities of students will not only be mixed; they will be unknown. Unlike public school settings, students with special needs will be anonymous and so their intervention needs will be unknown. Given there is no Title 1 help for students in the workplace (unless offered by the Department of Labor or its state offices) the trainer should be very sensitive to competency gains from the training. If gaps are identified, the trainer should be ready to adapt training methods for that student in order to build the needed competencies despite the challenges.
Most organizations do not apply such principles to internal training. They instead point to an individual and say "Go give XYZ training to 123 people."
So, what to do?
a) Develop and deliver your training to groups of people, in accordance with their responsibility and authority to business operations in the standard. This might be divided in as few as three groups to include production-level personnel, supervisory/middle management people, and upper-level managers. Are they tactical (fulfilling process-level orders), supervisory (overseeing the fulfillment of tactical orders in accordance with strategic initiatives) or upper management (creating strategic initiatives)?
b) Prepare your lesson to tell each group what they need to know in real-world, current, and hopefully objective-oriented terms.
c) For those cases in which trainees are not "mainstream" be ready to describe b) in more than one context. That is, visual/verbal/physical example.
Warning: this is a perfect-world scenario. The lack of the above spells out the gap between organized education (public/private schools, and colleges) and workplace training. I'm just bringing the points to light in the hopes they will help you provide effective training.