Math Background

Justifying Answers: Overview

Justifying answers sounds like common sense to us, but children need to understand why it is important and to learn strategies for doing it. They need to develop confidence in their ability to solve problems by telling what they did to solve the problem, why they did what they did, and why they think the answer they came to is the correct answer. Having children justify their answers conveys to them that math makes sense.

One way of helping children to learn to justify their answers is by asking good questions and having children talk about their thinking and reasoning as they answer the questions. Children will learn to model their thinking from your questions and from other students' explanations. Each day you should take time for discussion and writing about children's mathematical thinking and reasoning. Encourage a spirit of inquiry in your classroom.

One way for a child to justify answers is to look at the problem in a different way. One child might choose to draw a picture to solve the problem; another might use manipulatives or make a table to prove that an answer is correct.

Once children have decided on a plan for solving a problem, carried it out, and reached a conclusion, they need to look back at what they have done. Encourage children to read the problem again to make sure that they have all the information needed. Then they should look at the answer and think about what they did to get there. If the answer is reasonable, they have justified their answer. If their answer does not seem reasonable, they might want to try another approach.

To help with the process of justifying their answers, children should ask themselves several questions: Does the answer make sense? Why? Did I solve the problem correctly? If I solve the problem another way, do I get the same answer? Did I answer what the problem is asking?

To begin helping children solve word problems, you might want to write some problems on large sheets of paper. Then have children read them aloud and work through the problems as a class. Ask such questions as What does the problem tell you? How can you find the answer? Should you draw a picture, make a table, or use counters? Do you think you will add or subtract? Is your answer reasonable? and so on. Finally, encourage children to tell WHY they think the answer they arrived at is the correct one. Help children model lots of good questioning and thinking before they begin working in groups or on their own.


Houghton Mifflin Math Grade 1