In this article, Mann and Pynes describe a five-day mini-project-based learning (PBL) unit about organisms and their environments that addresses the "Next Generation Science Standards" (3-LS4-3). Third-grade students were asked how they could determine which animals live in their neighborhoods. In teacher-determined collaborative groups, students researched an animal that lived in their neighborhood, investigated evidence an animal might leave behind, and used what they learned to create two pages in their class book. When the mini project was completed, teachers reported being pleased with the interest and pride the students had in their work. As designers of the unit, Mann and Pynes were pleased that all of the teachers completed the PBL unit and expressed interest in trying other PBL units in the future.