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 4, 5:07
This is an example of the class discussing a problem that involves a person running a fixed distance in a certain amount of time. At this point the class understands that to have a constant ratio means the situation will be proportional. Notice how the teacher is keeping the students involved in the discussion.
The teacher changes the problem by having her starting distance being 200 yards, now creating a linear problem. The teacher again asks the question of whether or not the situation is proportional. Notice the teacher reminds them of the definiton they have decided on as a class.
