Hi Rosemary, how about something completely different. Let's say you have 12 in each training session. Split them into three groups of four and give them a department to go audit without a checklist, just use their eyes and write down what they think is wrong. Could be related to food safety, health and safety, quality etc. When they come back after an hour or so each team writes their findings on a board and discusses what the finding is, why it is a problem, what existing policy or procedure has failed (if there is one), the root cause and what should be done to correct, improve, prevent.
A rough idea and needs a bit of work...what do you think?