When you go to buy something, if you don’t buy it, you pay nothing. In other words, zero of that item cost you zero dollars. But if you do buy it, for each item that you buy, you will pay a certain amount. This is a description of a proportional relationship. If you were to graph this relationship, you would get a straight line going through the origin, (0, 0). Well, that’s exactly the focus for the activity, Proportional Relationships and Graphs!
In this activity, students examine graphs of proportional relationships. They focus on two special points on the graphs–the point at the origin, (0, 0), and the point that shows the unit rate.
Students begin the activity with a review of unit rates and quickly move to tables and graphs of proportional situations. Over the ten pages of the activity, students interpret points on the graph focusing on the point at the origin, and the point that represents the unit rate.