The teacher gives the students a problem that is both proportional and linear, then changes it so that it is still linear, but no longer proportional.
Comparing Proportional and Linear Situations, Clip 2, 2:11
In this example the teacher creates a situation where the previous problem is still linear but no longer proportional. The students are able to quickly alter their formula from the previous clip to create the linear model for the situation.
The teacher asks if it is proportional, again they create a table. The table gives them a way of checking for a constant ratio, and allows the teacher to show the students that it is NOT proportional, though they do recognize that it is linear. They again create the graph, recognizing that it is still straight, it just does not pass through the origin. They are exploring the differences in multiple representations.
