CRISPR-Cas9 is revolutionizing how we conduct scientific research, treat disease, and develop new crops. The widespread impact of this genome-editing technology makes it critical for undergraduate students to understand and engage with this new tool. In this article, we describe a multi-week lab module that teaches undergraduates how to design CRISPR-Cas9 constructs and screen for CRISPR-modified genotypes. The module is conducted through the lens of independent research; students conduct a genotype screen for novel knockout mutations. In our module, students screen Zea mays (maize) seedlings for mutations in the MAD2 gene, which assists our ongoing investigation of meiotic chromosome segregation. This module can be adapted to knockout any gene in any organism, and thus align with an instructor's research program. Engaging in original research helps undergraduate students develop independence and initiative in the lab as well as the molecular techniques of CRISPR-Cas9.