Here we discuss the design and implementation of an introductory DNA Barcoding module that we developed for the University of Hawai‘i at Mānoa’s Science in Action Program, a two-week summer program that teaches high school students about Hawai‘i’s biodiversity. Students used the concept of characterization to explain the relationships among organisms using morphological, ecological, and molecular data. Additionally, students gained experience in the scientific practice of generating explanations by gathering multiple lines of evidence to support or refute a claim, linking claims with evidence, and presenting such claims in written and oral formats to identify unknown algae samples. During this activity, students also gained real-world research experience in the field of biodiversity research. We also discuss potential modifications for future iterations of this module.