Video: Matching the Addition Expressions to its Models to Find the Answer and Identifying the Different Answer

Which of these has a different answer? [A] 3 + 3 [B] 1 + 5 [C] 3 + 4 [D] 2 + 4

02:19

Video Transcript

Which of these has a different answer? Three plus three. One plus five. Three plus four. Or two plus four.

We can see that these four different additions are also shown as a model using both blue and orange rectangles. Can you see what the first number in each addition represents? It’s the number of blue rectangles, isn’t it? For example, in the first addition sentence or equation, we have three blue rectangles. That’s why our first number is three. And we also have three orange rectangles. That’s why the second number in our equation is three. So what is three plus three? Let’s start by saying the first number and then counting on another three. So we’ll say three, four, five, six. There are six rectangles in our first model. Three plus three equals six.

In our second model, we can see that we have one blue rectangle and five orange rectangles, so we can start with the number one and count on another five. One, two, three, four, five, six. Our second number sentence also shows six. And if we compare the length of our models, we can see they’re both the same length. They both contain six rectangles, don’t they?

What about our next number sentence, three plus four. We’ll start with three and count on four. Three, four, five, six, seven. This number sentence has an answer of seven. And if we look at the length of the model, we can see that this is longer than the rest. The number sentence with a different answer is three plus four. We know this because if we start on two and count on another four, we’re going to arrive at six. Two, three, four, five, six. The addition that has a different answer is the one that shows three plus four.

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