Computers have made it easier for instructors to use simulations in their teaching. These are usually self-paced and fully automated, allowing the instructor to step back and watch students work. But this automation tends to illuminate the randomness and sudden changes that happen in a real-world environment. A patient might suddenly begin bleeding in the middle of an operation, requiring the surgeon to change plans, and a marketing team might be in the middle of planning a campaign when the boss suddenly changes the directive.