Interventions to promote learning are often categorized into supply- and demand-side approaches. In a randomized experiment to promote learning about COVID-19 among Mozambican adults, we study the interaction between a supply and a demand intervention, respectively: teaching, and providing financial incentives to learners. In theory, teaching and learner-incentives may be substitutes (crowding out one another) or complements (enhancing one another). Experts surveyed in advance predicted a high degree of substitutability between the two treatments. In contrast, we find substantially more complementarity than experts predicted. Combining teaching and incentive treatments raises COVID-19 knowledge test scores by 0.5 standard deviations. [Additional support for the working paper includes: Abdul Latif Jameel Poverty Action Lab via the Innovation in Government Initiative at the Massachusetts Institute of Technology, Innovations for Poverty Action via the Peace and Recovery Program at Yale University, and the Michigan Institute for Teaching and Research in Economics via the Ulmer Fund.]