Research shows that participation in school-based arts education has declined over the past decade. A problem for the arts' role in education has been a lack of rigorous scholarship that demonstrates educational benefits. A component of this problem has been a lack of available data. In this study, we use original data collected through a randomized controlled trial to measure the effects of school visits to an art museum. Building on previous work, we find positive effects of art museum visits on students' ability to critically examine a work of art. Importantly, we validate our previous findings with an additional experiment that utilizes a different style of art to assess critical-thinking outcomes, adding extra validity to the assessment instrument and our results. Our research suggests that policymakers should more fully consider the educational benefits of arts education, and scholars should consider broader approaches to measuring student performance in nontested subjects.