Dr. Meers, In numerous courses I have taught, I've restrained myself from using the element of surprise because of fear that it could backfire and completely cause the wrong effect. As a computer support instructor, I would find it fitting that computer technicians in training would benefit from ocassionally being surprised. For instance, one time I planned a drill that would have a student perplexed, encountering a computer that is malfunctioning after it was working perfectly fine before the coffee break. I've done this drill a few times with mixed success. One time, the students were able to succesfully fix the problem... another, they proceeded erroneously and even caused irrepairable damage. Yes, there was a learning experience, but I do not know to what extent it was positive or it was discouraging. After the incident I tried being supportive and debrief the students in order to ensure they understood what happenned... nevertheless, I had doubts as to whether reattempt to continue this approach. Are there any suggestions, in your perspective, that can provide some insight into delivering a "safer" positive effect while using a high impact surprise?