The Hardy-Weinberg equilibrium describes populations that are not evolving. There are five conditions that need to be met for a population to remain at the Hardy-Weinberg equilibrium.

• A large breeding population, with no genetic drift
• No immigration or emigration (gene flow)
• Random mating (no sexual selection)
• No mutations (no new alleles added to the gene pool)
• No natural selection (all traits aid equally in survival)

Go the The Biology Place web site, and read the following pages on the Hardy-Weinberg equilibrium.

• Start on the Key Concepts of Hardy-Weinberg
• From this page read the pages through Concept 6, use the interactives on the pages to check your understanding of the concepts. 

After reading those pages, watch the Brightstorm video, Hardy-Weinberg to get an understanding of the math you'll be using.