Economic research using a randomized control trial. Researchers split student research subjects into two groups. Treatment groups received a 50-minute lecture about how food affects climate change, along with information on the health benefits of eating less meat. Control groups received a lecture on a placebo topic. Individual-level data was collected by analyzing the students’ food choices in school cafeterias. Significant dietary change resulted from the single 50-minute lecture; subjects ate less meat and more plant-based alternatives. The effect lasted through the end of the academic year.