When you are investigating the relationship between two variables, one of the attributes that you should look for is the rate of change.

Linear functions have a constant rate of change, and nonlinear functions have a changing rate of change.

When an airplane takes off, it changes elevation at a certain number of feet per minute. If this change in elevation is constant, then the relationship between elevation and time since takeoff is a linear relationship.

Other relationships, such as the change in stock price over time, do not follow a constant rate of change. These relationships are nonlinear relationships.

In this resource, you will investigate special characteristics of rates of change of linear functions.