Empirical results in economics often succeed in controlled settings but fail when scaled up. This study introduces a behavioral intervention to reduce teacher shortages by motivating high school students to pursue education degrees, delivered via WhatsApp by human promoters (humans arm) and a scalable equivalent, rule-based chatbots (chatbots arm). The humans arm significantly increased high school students’ demand for and enrollment in education majors, especially among high-performing students. The chatbots arm showed positive but smaller statistically insignificant effects. The findings suggest that affordable interventions can help reduce teacher shortages, but successful scaling requires testing solutions during the experiment design phase.