Training engineers and technicians is a different kind of challenge - there are generally:
The worse case situation I have run into, was when another instructor and I were asked to instruct a class in statistics to technicians-in-training. These students were former operators - no previous technical or science training - participating in a fast-paced curriculum to quickly earn their associate's degrees in semiconductor technology.
So, these students are nearing the end of a long, intense, stressful curriculum, and are suddenly told, 3 weeks before graduation, that they must take one more course - a course in statistics, that would not involve any grades - the students just had to show up to the class.
Obviously, these students were motivated...NOT.
Within the first few days of the class, I had to stop the paper airplane construction from my handouts. It could have been worse... actually, it was worse for the other instructor. He made the mistake of leaving the classroom to get some materials from another room, and was locked out of the classroom.
As difficult as it is to discipline high school students, disciplining adults who are going stir-crazy from an intense curriculum that has taken them from their families, and that was supposed to be over 3 weeks earlier, is virtually impossible.
Actually, the story had a relatively happy ending. I decided to try to make the statistics course fun. I came up with some real life situations that they needed to optimize, had them use statistical methods in teams to solve the problems, and had the teams compete to come up with the best solution, the fastest.
The students had fun, they learned most of the material - and they got done with the curriculum.