BioEd Online has providing helpful resources for biology teachers for years, and they have recently placed this "ready-to-go" lesson online for use by educators. The basic objective of this particular resource is to have students learn to describe the functional differences of X and Y-chromosomes. To make this possible, the lesson includes four articles, worksheets, and several discussion questions. Instructors can also download a complete lesson plan, along with extensive notes. Finally, the site also includes information about the National Science Standards covered within this unit, along with an estimate of how long this unit will take to complete.