The *Rule of 4* refers to representing mathematical functions with *graphs, tables, equations*, and *words*. As learners discover how to represent functions in each of these ways, the mathematics becomes more meaningful. For example, consider the following cell phone plan offered by T-Mobile in 2011, represented using the *Rule of 4*.

**Words Representation (from website)**

Even More 1000 Talk + Unlimited Text

$59.99 includes 1000 whenever minutes

Additional minutes $0.45 per minute

Despite the fact that each of these representations of the cell phone cost function looks different, the same function is represented in each representation. All learners should practice to increase their ability to “see” the other forms mentally even when only one form is given.