This is the first of a series of Starter activities in which students are shown a movie of a mapping diagram and are asked to try to identify the function. [The mapping diagram provides an interesting contrast to the Cartesian graph which can help students discern the graph's characteristics.]
The values of x and y change continuously in the movie and are shown only fleetingly. Run the movie several times without pausing and ask students to describe what they see. 'How does the mapping arrow change?'
Now PAUSE the movie at judicious points. 'What is the relation between x and y?'
NOTE: If needed, you can download a free copy of the QuickTime movie player from here: