The instructions for this activity show a horizontal slider like the one used in Starlogo Nova. This slider allows the user to adjust the button to any number between 0 and 100. Often sliders are used to set an original number of agents or a population at the beginning of a program in setup. When programming an agent-based model, it is often necessary to have randomness and a percent chance that something might happen. For instance, if turtle collides with another turtle, there is a ‘percent chance’ that it will turn orange.