# Understanding SAT Math (Part 3 of 8): Linear Models

A **Linear Model** uses a linear equation to describe the relationship between two real world properties.

A simple example might be a child’s height versus their age. If after reaching a height of 2ft, a child’s height increased by a constant number of inches each year, it could be described by a linear model.

That equation might look like this: **H(eight) = 2.2A(ge) + 24**

To solve linear model questions, a student must first identity the **Rate of Change** - the slope of the linear equation - and get clear on what it means in the context. In this height versus age equation, ** the slope of the line is 2.2**. In this context that means that

**.**

*for every year the child ages, they are expected to grow 2.2 inches in height*In almost every case, the SAT question will be based on understanding the rate of change. A question might be, “How much taller will the child be in 3 years?”, or simply, “What does 2.2 represent in the equation?”

Linear Model questions are found mostly toward the end of math sections - sometimes the last question in a section. **They are expected to be challenging!** But once a students determines the slope and understands what it means, they’re rather simple to solve and a good opportunity to get points that many other students will not.