Insects have extraordinary species richness: over a million species have been identified, and even more await discovery and classification. Given their abundance and diversity, insects are excellent teaching tools for science classrooms. However, accurate insect identification can be especially challenging for beginning students. Accordingly, we have developed a dichotomous key that both precollege and university instructors and students can use efficiently to correctly identify 18 taxonomic orders of insects. Our key was developed to target insects most commonly encountered throughout the coastal southeastern United States, but it can easily be adapted to other regions. This key is novel in that it incorporates not only adult insects but also their immature stages. In addition, we included insects that are likely to be collected in all seasons, facilitating implementation in the classroom throughout the academic year.