Misinformation poses serious risks for democratic governance, conflict, and health. This study evaluates whether sustained, classroom-based education against misinformation can equip schoolchildren to become more discerning consumers of information. Partnering with a state government agency in Bihar, India, we conducted a field experiment in 583 villages with 13,500 students, using a 4-month curriculum designed to build skills, shift norms, and enhance knowledge about health misinformation. Intent-to-treat estimates demonstrate that treated respondents were significantly better at discerning true from false information, altered their health preferences, relied more on science, and reduced their dependence on unreliable news sources. We resurveyed participants 4 months post-intervention and found that effects persisted, as well as extended to political misinformation. Finally, we observe within-household treatment diffusion, with parents of treated students becoming more adept at discerning information. As many countries seek long-term solutions to combat misinformation, these findings highlight the promise of sustained classroom-based education.