Use a math formula

Teach this strategy when working with specific problems that can be solved efficiently using the same math equation each time. For example, it is most efficient to find area using the math equation area = length x width.

Mathematically proficient students recognize that using a formula is an efficient way to solve certain types of problems (such as circumference of a circle, area, volume, or distance). It is a quick way to find a solution, and the formula will work every time you need to solve this type of problem.

• For students to be successful with this strategy they must
• understand why the formula works the way it does, and
• know when the formula can and cannot be used to solve a problem.

Modeling a think-aloud during the “I Do” focus lesson: 
Explain to students that they are going to learn a math strategy that will help them use a specific math equation (sometimes called a math formula) to solve a certain type of math problem the same way, every time. Also, explain that a formula is an efficient way to solve certain types of problems because it works every time, and the more you work with it, the easier it will be to remember.

First, read through the problem. Then ask yourself if you’ve seen a problem like this before. If so, did a certain math formula make it easy for you to solve the problem? Or have you learned a certain math formula from your teacher or peers that would help you solve this particular problem? For example, when I am trying to find the area of a space, it is efficient for me to use the math formula area = length x width.

The more you work with specific math formulas, the easier it will become to recall and use them.

After modeling this strategy three or four times with several different math problems using whichever formula is being taught, we give students several more problems during the “We Do” focus lesson. Students practice using the formula to arrive at a solution.

Suggested Language

• Have I learned an equation, or “rule,” that will help me easily solve this problem?
• What is the most efficient way to solve this problem?

• It is more important to teach students why and how an equation works than it is to simply provide them with the equation.
• It is important to model and provide students with chances to practice when teaching them how to use a formula. They also need opportunities to learn and explore how to select the right formula for a given problem.

These strategies may provide support before, during, and after teaching this strategy:

• Draw a Picture
• Estimate
• Think-Aloud
• Look for a Pattern
• Create an Organized List
• Work Backward
• Monitor and Adjust