Metacognition, the ability to think about and regulate one's thinking, is an important factor in effective student learning. One intervention to promote student metacognition is the exam wrapper--a reflection students complete after an exam noting how their performance related to their preparation. Results are mixed on the effect of the exam wrapper use on student achievement in single STEM courses. In this study, we implemented exam wrappers in five large science and math courses and examined their impact on students' course outcomes, as well as students' self-reported behaviors on the Metacognitive Awareness Inventory (results for over 1,100 distinct individuals). Our data include a subset of students who completed exam wrappers in multiple courses simultaneously. We observed a modest but statistically significant positive relation between exam wrapper use and course grades in each course. The relation between exam wrapper use in multiple courses and cumulative grade point average was also statistically significant for male students. These results did not correlate with students' metacognitive awareness, however. These findings have important implications for how instructors construct and implement wrappers to maximize their potential usefulness.