In the afternoon, the students worked on their Vensim model. They learned how to use the different tools in this application. The class extended their previous model by adding a predator to the model. Since they were modeling an M&M population, they created humans as the predator. The students had humans being born and dying, and showed how the two populations were interdependent. The humans would eat the M&Ms, but when there were not enough M&Ms, the humans would begin to die off, then the M&M population would grow, and so on.