Scientists have discovered that microplastic pollution is ubiquitous in the environment, but the small size of these microscopic pollutants prohibits most people from recognizing their prevalence. This river-based field lesson will introduce environmental science students to this emerging environmental concern, and encourages them to explore microplastics in their local waterways with sample collection, density separation and field-based microscopy. Students will appreciate the opportunity to connect to this topic from anywhere in the world, allowing them to see microplastics with their own eyes and without the use of sophisticated equipment. In addition, this lesson helps students recognize their own personal impact on microplastic pollution and identify ways to reduce their creation of microplastics.