At the core of an effective model-based inquiry (MBI) unit is a scientifically rich, complex phenomenon that serves as the reason for engagement and drives student sensemaking and investigations throughout the unit. Engaging in iterative attempts to explain phenomena over the course of an MBI unit allows the opportunity for students to construct evidence-based explanations that are refined over time with various science practices. This article provides an example of using MBI as an instructional model to facilitate students' conceptual understanding of chemical reactions. Over the course of 14 days, in 50-minute class periods, high school chemistry students developed a deep conceptual understanding of chemical reactions and the role they play in airbag design and safety through a variety of investigations and activities aligned to the "Next Generation Science Standards." Students were then able to apply their knowledge to an airbag engineering design activity. To focus on the engineering design aspect of this activity, it is recommended this task be used as the culminating activity to a unit on chemical reactions.