Contribution: This paper presents evidence demonstrating ways in which flexible classrooms (which have movable tables and chairs that can be rearranged into different layouts) afford active learning. It highlights the quantitative increase in active learning that occurs for one instructor and discusses how the affordances of the flexible classroom support qualitatively better instructor-student and student-peer interaction during active learning. Background: Research has shown that students benefit from active learning, but instructors still perceive many barriers to implementing it. Flexible classrooms may reduce some of these barriers, and their affordances may promote better student engagement and allow instructors to use more active learning than traditional lecture-style classrooms do. Research Questions: What are the differences in the amount of active learning used by an instructor between flexible classrooms and traditional classrooms? How do instructors and students use the affordances of flexible classrooms during active learning? Methodology: An instructor at a large Midwestern university taught the course Introduction to Electronics Circuits in a traditional classroom one semester and in a flexible classroom the next. The two research questions were addressed through complementary quantitative and qualitative analyses of video data, classroom observations, and instructor interviews to detail the amount of active learning and the way the instructor facilitated it in the flexible classroom. Findings: The time the instructor devoted to active learning increased in the flexible classroom, while the time she devoted to instructor-led examples decreased. The affordances of the flexible classroom also encouraged more frequent and better student-instructor and student-peer interaction.