Question Video: Exploring Different Ways to Make 6 Mathematics • 1st Grade

Find the missing addition sentence.


Video Transcript

Find the missing addition sentence. Zero plus six is six. One plus five is six. Two plus four is six. Three plus three is six. Four plus two is six. What? And we have four possible answers. Four plus one is six. Four plus two is five. Five plus one is six. And four plus one is five.

In this question, we’re given some addition sentences. These are written using numbers, but they’re also modeled using cubes. And we can see both orange and green cubes here. The first line of cubes shows no green cubes and six orange cubes. That’s where we get our number sentence zero plus six from. We can think of the first number as being the number of green cubes that we can see and the second number as being the number of orange cubes that we can see. And because the length of each line of cubes is the same each time, these are always going to make six. Zero plus six is six.

We can also see that one plus five is six. Two green cubes and four orange cubes make six. If we add together three of each type of cube, we get six. Four plus two make six. But then we come to a missing addition sentence. And the question asks us to find out what it is. What can we say about this missing addition sentence? Well, firstly, we can say that we’re looking for two numbers that we need to add together, just like all the other addition sentences. We can also say that we’re looking for a number sentence that gives the answer six.

If we look at our line of cubes, we can see that there are six cubes just like all the others. So which two numbers can we find that make six? If we look at the numbers in each addition, we can see some patterns. The first number in each addition, which is the number of green cubes, increases by one each time. If we read each of the first numbers, we can see zero, one, two, three, four. If we’re increasing by one each time, what’s going to come after four? We’d expect to see the number five. Should we count our green squares to see whether that’s correct? One, two, three, four. Yes, there are five green squares.

And if we look at the second number in each addition, which is the number of orange squares, we can see that these decrease by one each time. They get smaller. Six, five, four, three, two. What comes after two? One. How many orange squares are in our line of cubes? One. So we would expect our missing addition sentence to say five and one is six. Can you see that as one of our possible choices? Yes, here it is. Five plus one is six.

Using cubes like this is a really good way to model all the possible ways to make a number. In fact, there is only one other way that isn’t shown. A line of just green cubes would show us that six plus zero is six too. But we don’t need to know this to answer the question. The missing addition sentence from the picture that we were shown is five plus one is six.

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