These are two associated clips. Each clip has an associated transcript. In the study group video, teachers have watched a clip from the classroom of one of the participants, in which students try to describe how the angle at which sunlight strikes earth relates to intensity of heat received by earth; they consider whether light striking at a greater angle covers more surface area, so therefore has less intensity. The facilitator notices teachers’ content understanding as they are discussing students’ ideas, and asks teachers to articulate their own scientific understanding. In the associated classroom clip, one teacher from the study group teaches the next lesson in the lesson sequence and uses his new understanding of the science concepts to guide students in integrating ideas about the intensity of light striking a given latitude as the Earth orbits the sun at consistent tilt over the course of a year.