During an eight-week series of investigations, a class of third-grade students learned how interactions between forces are used to advance technology in their world. This five-part forces and interaction unit was led by a guiding question: How does engineering and design work in the world, and how does it affect our lives? As they explored this question, students were exposed to real-world examinations of the subject matter, such as the history of the compass, discoveries of Earth's magnetic core, inventions like maglev trains, and lifesaving MRI machines. This unit emphasized the crosscutting concept of cause and effect while also having a strong engineering and design focus, allowing students to deeply examine the process of design and begin to form understandings of the causal relationships associated with forces and interactions. The Forces and Interaction unit was a challenging unit to turn into an interesting curriculum piece. Physical sciences have typically been taught as a series of experiments and activities seemingly disconnected from our lives. Yet they are used and present in our lives each and every day. Incorporating engineering design practices and crosscutting concepts as the big ideas of the unit required a different mindset--one that was creative and oriented in real-world applications with opportunities to develop a different kind of thinking.