You might break your training day into 4 modules, for instance, and after each one is completed, break the group into 4 teams and assign each one a section of the workbook you've just covered. Give them 10 minutes as a team to pick out what they consider to be the most important points and then present that material back to the class in their own unique way. They might choose to have one group reporter or present as a team. You may also do this once at the very end of a training session as a form of review. When I have a 2 day class, I have them teach what they learned on the first day, at the beginning of the second day.
People remember best what they are responsible for teaching to others.
This technique also gives you great insight into what your audience felt was the most important or valuable to them.