For Algebra teachers we know there are certain "go-to" graphs of functions that tend to be most popular in our texts. Having the ability to recognize these graphs enables the student to anticipate the shape of the graph and any of its variations. Simply knowing its normal shape allows students to visualize any transitions or reflections in the graph.
The point of this exercise is to send your students on a scavenger hunt in nature for the graphs of functions. Such an exercise would make a great recess or study hall period activity as well as an end of the class exercise.