"Survival of the Fittest—Battling Beetles" is a guided inquiry. This series of activities complements the HHMI DVD Evolution: Constant Change and Common Threads, and requires simple materials such as M&Ms, food storage bags, colored pencils, and paper cups. An extension of this activity allows students to model Hardy-Weinberg and selection using an Excel spreadsheet. This part of the activity requires computer/printer access. The overall goal of Battling Beetles is to engage students in thinking about the mechanism of natural selection through data collection and pattern recognition.