Define, evaluate, and compare functions.

8.F.1 Understand that a function is a rule that assigns to each input exactly one output.

8.F.2 Compare properties of two functions each represented in a different way.

8.F.3 Interpret the equation y = mx + b as defining a linear function, whose graph is a straight line. Give examples of functions that are not linear.

Use functions to model relationships between quantities.

8.F.4 Construct a function to model a linear relationship between two quantities. 

8.F.5 Describe qualitatively the functional relationship between two quantities by analyzing a graph. Sketch a graph that exhibits the qualitative features of a function that has been described verbally.