At the start of this lesson, students participated in a “What do you notice? What do you wonder?” activity. They were given an image, graph, or set of numbers and asked first to make observations, then to pose questions about what they saw. This curiosity-driven warm-up led naturally into the day’s main topic: triangles. Together, the class explored how triangles are defined by their sides and angles, and what conclusions can be drawn about different types based on those characteristics. This lesson marked the beginning of their unit on right triangles—an essential foundation of the Class IX curriculum and a springboard for many of the topics students will study next.