Globally, most human caloric intake is from crops that belong to the grass family (Poaceae), including sugarcane (Saccharum spp.), rice (Oryza sativa), maize (or corn, Zea mays), and wheat (Triticum aestivum). The grasses have a unique morphology and inflorescence architecture, and some have also evolved an uncommon photosynthesis pathway that confers drought and heat tolerance, the C₄ pathway. Most secondary-level students are unaware of the global value of these crops and are unfamiliar with plant science fundamentals such as grass architecture and the genetic concepts of genotype and phenotype. Green foxtail millet (Setaria viridis) is a model organism for C₄ plants and a close relative of globally important grasses, including sugarcane. It is ideal for teaching about grass morphology, the economic value of grasses, and the C₄ photosynthetic pathway. This article details a teaching module that uses S. viridis to engage entire classrooms of students in authentic research through a laboratory investigation of grass morphology, growth cycle, and genetics. This module includes protocols and assignments to guide students through the process of growing one generation of S. viridis mutants and reference wild-type plants from seed to seed, taking measurements, making critical observations of mutant phenotypes, and discussing their physiological implications.