Abstract Evolution and its mechanisms of action are concepts that unite all aspects of biology, but remain some of the most difficult for students to understand. To address this challenge, we designed a hands-on activity that introduces fundamental mechanisms of evolutionary change: natural selection, genetic drift, and gene flow. In small groups, students use a population of sticky notes to reveal the consequences of each mechanism on phenotype frequency. In a follow-up homework assignment, students then explore how changes in phenotype frequency reflect changes in allele frequency in the population. This activity is suitable for anyone learning the basics of evolution, from high-school through the undergraduate level. We have provided det...