From @mres: "This is a simulation of the spread of an epidemic. Use the slider to control what percentage of the population stays at home, then click the Green Flag. The graph shows how the number of sick people changes over time Color Code: Healthy/Blue, Sick/Red, Recovered/Green"
This is a version of @mres' epidemic simulation that has been modified to include code comments. I also made the sick variable visible so you can see how many people of the original 100 are sick. As for his code modification suggestions: *To change the speed of recovery, change the value of the time to recover variable. *To change the number of people in the community, change the number of times the create clone of myself block repeats. *To make the virus spread probabilistically (so there is a chance to catch it when interacting with someone who is infected instead of a guarantee), create a block similar to the one that checks whether or not the sprite stays at home.