Background: Experts agree that the promotion of (digital) health literacy should be an integral part of the school curriculum. However, promoting (digital) health literacy within the German school system is difficult because (digital) health education is not a mandatory school subject in all the German states. Therefore, experts suggest that (digital) health literacy could be addressed as part of the mandatory framework for digital education and digital literacy in schools developed by the German Conference on Education Ministries and Cultural Affairs (Kultusministerkonferenz). Objective: The goal of this study was to evaluate a newly developed e-learning course that was designed to improve (digital) health literacy in school-age children and concurrently to teach skills specified in the mandatory framework for digital education and digital literacy in schools. It was hypothesized that participants' health literacy and digital health literacy levels would be higher after completing the e-learning course than they were before doing the course. Furthermore, it was hypothesized that after completing the e-learning course, participants' subjective and objective knowledge in the domain of (digital) health literacy would be higher than it was before doing the course. Methods: The pre-post measurement study was conducted online. After participants (N=323) gave their informed consent to participate in the study, they provided demographic information and answered all measures (premeasurement). Following this, participants had 7 days to complete the e-learning course. After finishing the e-learning course, participants answered all the measures again (postmeasurement). Results: To test the hypotheses, Bayesian paired samples t tests (1-sided) were conducted. After completing the e-learning course, participants showed higher health literacy levels. Specifically, they showed higher competency levels in the domains of theoretical knowledge (Bayes factor [BF](-0)=676,000; delta=-0.316), practical knowledge (BF-0=92,300; delta=-0.294), critical thinking (BF-0=7.42e+13; delta=-0.482), self-awareness (BF-0=11,500,000; delta=-0.345), and citizenship (BF-0=266,000; delta=-0.306). Furthermore, participants achieved higher digital health literacy levels. Specifically, they achieved higher competency levels in the domains of information searching (BF-0=2.339; delta=-0.135), evaluating reliability (BF-0=2.03e+11; delta=-0.434), and determining relevance (BF-0=316,000; delta=-0.308). Moreover, participants demonstrated higher subjective (BF-0=3.58e+82; delta=-1.515) and objective knowledge (BF-0=3.82e+97; delta=-1.758) in the domain of (digital) health literacy. Conclusions: The newly designed e-learning course provides an easy way for schools and teachers from all German states to integrate (digital) health literacy education into their school curriculums and lessons. The evaluated course is especially attractive because it was designed to improve (digital) health literacy and at the same time to teach skills specified in the mandatory framework for digital education and digital literacy in schools developed by the German Conference on Education Ministries and Cultural Affairs (Kultusministerkonferenz).
