The study of shadows is a common elementary science topic that facilitates students' development of understanding about light and associated waves. All elementary students have observed numerous shadows, but need assistance in developing understanding. Previous research studies about shadows were utilized in organizing aspects associated with shadows. This review paper encourages teachers to utilize three principles of learning: students' prior knowledge about shadows, factual and conceptual knowledge related to shadows, and metacognition requiring students to think about their personal understanding about shadows; thereby, promoting students' science literacy.