This variation on the classic bird beak activity demonstrates variation of beak size within a population and shows how the proportion of big-, medium-, and small-beaked birds changes in response to the available types of food. The birds with binder clip beaks live in Clipland where the large population becomes divided into two smaller populations by a mountain range. Popcorn, lima beans and marbles are the three types of food available in the two areas. Food is spread out for the birds to eat and then after 15 seconds it is counted to see whether birds have gathered enough food to survive. The big billed birds need to eat more than the medium and small billed birds to survive and each bird needs to eat more than the minimum amount of food for survival to be able to reproduce. Four years pass during the simulation and students are asked to describe what happened to the Clipbird populations and what they think caused the changes. A link to Rosemary and Peter Grants research on finch populations in the Galapagos is identified for those teachers who want to connect the simulation to a real life example.