Rivers twist and turn as they make their way to the sea. Why does this happen and how can this be explained mathematically? In this module we look at the geometry of meandering rivers. In the process we'll discover some fascinating numerical relationships.

Have you noticed how wrinkled an elephant's skin is? What purpose does it serve and what does math have to do with explaining this phenomenon? Well, the explanation for an elephant's wrinkled skin is almost entirely a math story. 

As the size of a circle changes, so does the size of the diameter and that of the circumference. In fact, there is a linear relationship between these two measures. This relationship can be modeled with a linear function.

Temperature is one of the most important measurements that we deal with on a daily basis. Weather, climate, food preparation, health, and other phenomena involve some type of temperature measure. The two most common units of temperature measure are Fahrenheit and Celsius.

Turn the Halloween season into an opportunity to do some math activities! In this module, you'll find a clever collection of arithmetic, algebra, and geometry activities.

In this real-world application of ratios, students will learn what a ratio is, including ratios with three terms. They will see different ways of writing ratios, including fractions in simplest form.