Detective's Case Reports

Year 3: Explaining Your Problem-Solving Methods

Your Assignment, Detective!

For each case below, you need to not only find the answer but also explain how you solved it. Write down your steps clearly, as if you're writing a report for the Chief Inspector!

Be a Maths Teacher for a Moment: Explaining How You Solved It!

Hello Maths Superstars! You're brilliant at finding answers to maths problems. But do you know what's another super important skill? Being able to explain the method you used to get that answer! It’s like being a maths teacher and showing someone else your amazing thinking. Today, we're going to learn how to clearly explain our problem-solving steps.

Why is Explaining Your Method So Important?

What Makes a Good Maths Explanation?

Example 1: Explaining a Mental Addition Problem: 56 + 32 = ? Your Answer: 88 Your Explanation Could Be: "First, I partitioned the 32 into 30 and 2. Then, I added 56 + 30, which is 86. After that, I added the 2 to 86, which made 88. So, 56 + 32 is 88."

Example 2: Explaining Column Subtraction with Regrouping Problem: 71 − 24 = ? Your Answer: 47 Your Explanation Could Be: "I set it up as column subtraction. In the ones column, I couldn't do 1 take away 4. So, I regrouped 1 ten from the 7 tens, making it 6 tens. The 1 one became 11 ones. Then, 11 take away 4 is 7. In the tens column, 6 tens take away 2 tens is 4 tens. So, the answer is 47."

Example 3: Explaining a Choice in a Word Problem Problem: "There were 120 fish in a tank. 35 more fish were added. How many fish are there in total?" Your Answer: 155 fish Your Explanation Could Be: "The problem asked 'how many fish are there in total' and said 'more fish were added.' These words told me I needed to add the numbers together. So I added 120 and 35 to get 155 fish."

Practice Explaining Your Maths Methods! (18 Activities)

Ready to become a super maths explainer? For the activities below, you might solve a problem and then explain your method, or you might look at a solved problem and choose the best explanation. Think clearly about your steps!

*(Your web app with the 18 activities will go here. These could involve:

Why is Being a Good Maths Explainer a Top Skill?

Tips for Grown-Ups: Encouraging Mathematical Explanations

Encouraging children to explain their problem-solving methods is vital for developing deep mathematical understanding, reasoning, and communication skills. It moves them beyond procedural knowledge to conceptual understanding.