Introducing green chemistry principles to high school students, through a student-directed, inquiry-based critical analysis of how experimental “success” is measured. Students design a precipitation experiment and develop success criteria for it, without prior knowledge of yield calculations or green chemistry metrics. Subsequently, they perform a green chemistry experiment and critically assess reaction yield against green metrics. Specific learning objectives, evidence of their achievement, and evidence of student learning are presented. Justification for teaching green chemistry metrics (specifically process mass intensity) is provided and recommendations for curricular reform are proposed.