A five-week research project was designed as part of a summer internship for high school students, and could also be used with educators or in introductory undergraduate research courses. This is a guided-inquiry-based project, framed within the significant issue of supplementing fertilizer use in agriculture with nitrogen-fixing microorganisms. This experience exposes students to how scientists are studying real-world problems; it teaches them basic research techniques, and promotes inquiry-based learning in a real research environment. It also fills a current gap in K-12 education that lacks enough microbiology emphasis. Research interns collect soil samples from various fields and use culture-dependent and culture-independent techniques to test whether there are nitrogen-fixing microorganisms that can be isolated and identified in each soil sample. Students work in a research laboratory making nitrogen-free media; culturing, isolating, and identifying microorganisms; extracting soil DNA; and amplifying the 16S rRNA and nifH genes. We administer a pre-test and a post-test, and students present their research both in a short talk and with a poster. By hosting high school students in a research laboratory and immersing them in laboratory science, we hope to inspire them to pursue a STEM-related career.