Video Transcript
Use six plus 13 equals 19 to fill
in the blanks in these number sentences. 13 plus what equals 19. 19 subtract six equals what. And what take away 13 equals
six.
To begin with, in this problem,
we’re given an addition. It’s an addition that’s a complete
number sentence. We can see the two parts that we
add together and the answer. So we could sketch a part–whole
model to represent it. Six and 13 make a total of 19. And you know, we can use these
three numbers, the two parts that go together to make the whole, to help us fill in
the blanks in some different number sentences. And the reason why we can do this
is that the three number sentences we’re given with blanks in are all related;
they’re part of a family. You’ll see why, as we go through
them.
Our first number sentence says, 13
plus what equals 19. Can you spot anything interesting
about this addition? The first thing that we can see is
that the total, the answer to our addition, is 19. It’s the same as the total in the
addition we need to use to help. And if we keep looking, we can also
see that the number we’re starting with here, which is 13, is the second number in
our addition. And so if six plus 13 make 19, then
we know that 13 plus six makes 19 too. We’ve just added the same two parts
but in a different order.
Our second calculation is a
subtraction. 19 take away six equals what. Well, we know from our last
calculation that 13 plus six more make 19. So if we start with 19 and we take
away six, we’re going to be left with 13. Each of these calculations contains
the same three numbers, 19, six, and 13. That’s what we meant when we said
they were going to be related.
Our final calculation is what take
away 13 equals six. Well, again, we can use the
addition to help us find the subtraction. If we know that six and 13 go
together to make 19, then we also know if we start with 19, the whole amount, and we
take away one of the parts ,13, we’re going to be left with six. The missing number here is 19. We’ve used six plus 13 equals 19 to
fill in the blanks and find a family of addition and subtraction sentences. 13 plus six equals 19. 19 take away six equals 13. And 19 take away 13 equals six. Our missing numbers are six, 13,
and 19.
