Check solution using a different method

If you see students who . . .

• rush through their work.
• make minor errors in their work.

This strategy benefits all mathematicians and should be introduced and employed by all.

Mathematically proficient students need this strategy because it helps them attend to accuracy and precision in their work. Additionally, it gives them a tool to help them confirm when their work is correct or to recognize and correct any errors.

For students to be successful with this strategy they must be able to

• calculate accurately and efficiently,
• have flexibility in their thinking,
• be able to explain their work, and
• be able to reason abstractly and concretely.

Modeling a think-aloud during the “I Do” focus lesson:
Explain to students that they are going to learn how to Check Their Solution Using a Different Method. This helps us confirm that we have done the work accurately or see when we have made a mistake. One way to do this is to use a strategy that is different from the one we first used to solve the problem.

This strategy is important because it helps us attend to accuracy and precision in our work. Additionally, it gives us a tool to help us confirm when our work is correct or to recognize and correct any errors. This strategy can be used all the time to help make sure that our work is free of mistakes.

Using the strategy Check Your Solution Using a Different Method looks like this:
Once you have solved a problem and found a solution, choose a way to solve the problem that is different from how you did it the first time. Use this method to solve the problem and ensure that you still arrive at the same solution. You will know you are using this strategy when you can easily explain how you arrived at a solution, your work makes sense, and your work is regularly free of mistakes.

Suggested Language

• What is another method I can use to solve this problem?
• How can I check my solution so that I know I have done my work correctly?

• Teach students to mark up the problem.
• Teach students to look at how the problem is organized to determine if they’ve already seen and solved a similar problem.
• Introduce students to multiple ways to solve the same type of problem. (Mental math is excellent for showcasing this.)
• Give students a T-chart organizer. Students can use the left side to solve their problem. They can use the right side to check their solution using a different method. The student’s work can be used as a launching point during individual conferences.

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

• Guide to Using Math Tools
• Check My Work