Justifying AnswersJustifying answers sounds like common sense to us, but children need to be shown strategies for doing so, and why it is important. Children need to develop the confidence in their ability to solve problems. In simple language, children need to be able to figure out problems, tell what they did to solve the problem, why they did what they did, and why they think the answer they came to is a good 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/or writing about students' 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. Perhaps a child might chose to draw a picture to solve the problem; another way might be to use manipulatives or make a table to prove that he or she 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. They should 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 the 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 figure the problem correctly? If I try another way, do I get the same answer? Did I answer what the problem is asking? To begin helping children solve story 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, or maybe a table, or use counters, etc.?", "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 is the one they arrived at. Help children model lots of good questioning and thinking before they begin working in groups or on their own.




Show story problem, solved:
Sam has 3 marbles.
He finds 3 more marbles.
How many marbles does Sam have now?
3 + 3 = 6 marbles Child is looking at what he/she has done and is thinking (thought balloon): How can I make sure my answer is correct? Can I try it another way?] 
