# Independent and Dependent

## Opening

# Independent and Dependent

**Read and Discuss**

- You’ve seen many quantitative relationships—for example, the relationship between distance and time when you’re riding your bike. In these relationships, the quantity that changes independently is called the
*independent variable*, and the quantity that is calculated is called the*dependent variable*. - In the above relationship, distance is the dependent variable because your distance depends on the amount of time that has passed. Time is the independent variable because the amount of time that has passed really does not depend on how far you have gone.
- You graph the independent variable on the horizontal axis, the
*x*-axis, and the dependent variable on the vertical axis, the*y*-axis. There isn’t any great mystery behind this; it’s just something mathematicians and scientists agreed on so that everyone would graph things the same way.