1. Class 23, November 19, 2015 Lesson 4.2

2.  By the end of this lesson, you should understand (that): ◦ Linear models are appropriate when the situation has a constant rate of increase or decrease, or can be approximated by a constant rate ◦ The rate of change (slope) has units in context ◦ The difference between a positive and a negative slope ◦ Linear models for authentic situations have limitations in using them to make predictions

3.  By the end of this lesson, you should be able to: ◦ Make a linear model when given data or information in context ◦ Calculate a slope, given data or information in context ◦ Estimate the value that makes two linear models equivalent

4.  Main idea: ◦ A slope is a rate with units. It can be thought of as the rate of change between two data points. In the case of nonlinear data, this is an average rate of change.