Field trips are wonderful opportunities to expand student learning, but the bus rides can be challenging. Perched in the first row, teachers attempt to guide the driver while tossing repeated reminders of safe bus behavior to the students in back, inevitably arriving at the destination flustered and possibly nauseated. In this article the author describes how she and her colleagues addressed the issue of stressful bus rides by focusing their second-grade studies closer to home, within walking distance of school. They developed a series of units integrating science, social studies, math, and literacy around the single focus of our local river. They begin their yearly river unit by collecting questions students have about the river. Some of the things students would like to know typically include: Where does the river start? Where does it end? Where does it come closest to our school? These questions launch a mapping unit that culminates in their first engineering design challenge: Create a tool to measure length, width, or depth of the river. As students design, construct, test, and improve their tools, they build a deep understanding of the challenges and rewards of the engineering process. They learn how to collect, analyze, and evaluate data and gain a greater understanding of the issues encountered while trying to create a map or model of a particular location. This design challenge engages students in conversations about what it means to be "measurable" and encourages them to examine what is "measurable" about a river. This guided-inquiry activity also promotes collaboration and sets the tone for a year of hands-on exploration with real-world applications. This article describes the design activities in detail as they evolved over a period of five years. It provides a model for teachers in the elementary grades who wish to replicate the process in their own settings.