Research mentors can play an active role in helping their students develop oral communication skills by implementing formative assessment activities in their group meetings. A rubric can be used as a formative assessment tool that helps a student understand the achievement target they are working toward, where they are relative to the achievement target, and how to close the gap between where they are and where they need to be. In this article, we present a rubric-based activity to help undergraduate students develop scientific oral communication skills during their summer undergraduate research experiences. Our approach uses a rubric of our own design to help guide students through metacognitive reflection to improve their oral presentations. Here, we present findings on the effectiveness of this rubric-based activity and discuss its implications on student growth. While our results focus on undergraduate student development in the research laboratory, we expect this activity can also be used in training graduate students to give effective scientific presentations.