Illuminations: Bathtub Water Levels
Illuminations (National Council of Teachers of Mathematics)

This lesson is similar to Lesson One: Traveling Distances; however, this lesson is designed so students examine real-life data that illustrates a negative slope.

Illuminations: Automobile Mileage - Year vs. Mileage
Illuminations (National Council of Teachers of Mathematics)

In this lesson, students plot data about automobile mileage and interpret the meaning of the slope and y-intercept in the resulting equation for the least squares regression line.