In this part of the lesson, the teacher is talking through the last lesson and the homework, using mathematical language such as point of intersection, rate of change, systems of equations, simultaneous equations, x-axis, y-axis, equations, and scale. The teacher uses questions to engage students in using the mathematical language.

In this part of the lesson, students are observed working on grade-level problems. The teacher is circulating the room, asking questions of students, supporting students with the mathematics, and modeling for students how to complete the activity.

In this part of the lesson, students are comparing answers, asking questions of each other such as, \"How did you get negative 1?\" and explaining their thinking.

In this part of the lesson, the teacher is supporting a student who is asking for help. She uses questions to gather evidence on student understanding and then engages the student\'s partner in explaining how he solved the problem.

In this part of the lesson, a student shares his confusion about the task. The teacher supports his developing understanding using questioning and relating what he is having difficulty with to the previous problem (which he was successful with). She guides the student\'s thinking so he determines he needs to change the equation to slope-intercept form. The problems are challenging in that they need to be rewritten in slope-intercept form. As the teacher walks away, the students get to work, persevering despite initial difficulty.

This clip illustrates how this task helps develop students\' conceptual understanding. The students are explaining why and how you have to solve for y in order to change an equation to slope-intercept form. The teacher uses \"why?\" to get students to share their thinking.

Here, the teacher has returned to a student she worked with earlier to check in with him. He demonstrates understanding of what slope is and means and where to place the y-intercept. He is having difficulty changing equations into slope-intercept form, so the teacher gives the student the equations in slope-intercept form so he can work on graphing the equations and identifying the point of intersection.