I feel that to disarm any possible problem or angry or silent students the best way is to involve every one from day one. Set the guidelines, objectives, policies, procedures and what ever else needs to be covered in your particular class, then ask for input on their opions. This usually gets them thinking with little or no response. Then half way into the course I ask them again to what thier ideas, feeling and thoughts are on the curriculum at this stage of the course. I get alot of input even from the silent students. I ask what can I do better, how can we as a group make the course better, so on and so forth. On the final day I ask them again, so I keep them engaged in the subject matter through the course, ask for possible changes and improvements, what works what doesn't work, and where can we interject something completely new and differant. I find that most angry students get that way because they fell that no one cares or will listen, engage them before they engage you and this disarms them and makes them work with you to find improvements and answers. I know that we can't always get away from some problems but this had worked for me for some time now.