Video Transcript
Ethan is adding by making 10. Nine plus six equals what. Which calculation should he do
first? Nine plus one equals 10 or nine
plus five equals 14. And then which calculation should
he do next? 10 plus six equals 16 or 10 plus
five equals 15.
In this question, we can see that
Ethan is adding two one-digit numbers together, nine plus six. And in the first sentence, we’re
told how Ethan does this. He’s adding by making 10. Now, if Ethan wants to add nine and
six together, why might he want to make 10? Or perhaps he knows that adding any
number to 10 is a quick and an easy way to find an answer. And if we look at the diagram, we
can see what Ethan’s done. We can see that he started off by
writing the addition nine plus six. But he’s done something interesting
to the number six. He split up the number six using a
part-whole model. And he split it into the number one
and five because one and five are two parts that go together to make six.
Now, why might Ethan have split the
number six into one and five? Well, he wants to make 10. That’s why. And Ethan knows that if he puts one
with nine, he can make the number 10. That’s how we know the calculation
that Ethan should do first is nine plus one equals 10. Now, adding a number on to 10 is a
quick and easy thing to do. So all Ethan needs to do to find
the total is to add what’s left of the number six, the other part, which is
five. This is how we know that the
calculation Ethan needs to do next is 10 plus five equals 15. Ethan found the answer to nine plus
six by splitting up the number six and using it to make 10. His first calculation was nine plus
one equals 10. And then he added what was left of
the number six. 10 plus five equals 15.
