This simulation illustrates how inventions, jokes, diseases, and memes spread through a population.
  • Blue circles represent individuals who have not been exposed (they've never heard the joke, or contracted the disease).
  • Red circles represent those who have recently been exposed.
    • Over time, the red circles fade to orange and yellow and finally green.
    • While they are red or yellow, the circles are contageous (they tell the joke or sneeze on people)
  • Green circles represent those who have become immune (they've heard the joke so often they don't even smile, or they've developed antibodies to the disease). Green circles are not contageous, and they cannot become re-infected.

  • The upper box will show a graph of the total number of affected people over time                       
PREDICT: What do you think the graph will look like?
How many of the 200 blue circles will be left in the end?

Tap on one of the circles to begin the infection.