This free, standards-based, online publication, developed for middle school science teachers, explores evolution. Your middle school students, who in elementary school considered life science from an individual organism perspective, are beginning to think about interactions in ecosystems. In high school, they will broaden their biological perspective to include both smaller and larger realms, considering everything from biochemical processes to living systems in the biosphere. Now is a perfect time to help your students get a firm grounding in the basics of evolution so that they will be prepared to tackle more abstract concepts in high school, such as population genetics and evolution as a basis for biological classification. The scientific habits of mind that they develop as they study evolution will support all of their future scientific endeavors.