"Ants on a Rock" is a 20 minute review worksheet covering natural selection, phenotypic variations in populations, Hardy-Weinberg, and allele frequency. Students are asked to determine the percentage of heterozygotes at the end of generation 5, the color of rock the ants live on, and what selective pressures are at work in this population. This product is great for individual homework, group work in class, or as an exit ticket. The science practice addressed is performing data analysis. The essential knowledge addressed is "natural selection acts on phenotypic variations in populations."