In terms of Mathematics, mathematicians, game theories, and economists use simulation to show and analyze probabilities and statistics in theoretical events. In addition, in the field of medical, students and professionals use simulation tools to perform and practice such surgical procedures, first aid (like CPR), and such. For example, in aviation (related to the business or practice of flying airplanes, helicopters, and etc.), where they spend many hours practicing in flight simulator before flying in a real aircraft. Simulation and models provide interactive controls and activities where learners can vary any parameters in specific models and see time changes in the outcome.