Liam had nine toy cars. He lost three of the cars. He can work out how many are left
by completing either of the following number sentences. Nine take away three equals
what. Three plus what equals nine. How many cars are left?
This is a subtraction problem. We know that Liam had nine toy cars
and he lost three of them. We have to work out how many cars
he has left. This part–whole model helps us
think about how to solve the problem. We know the whole amount or the
number of cars Liam had to begin with is nine. We know that one of the parts or
one of the numbers that go together to make nine is the number three because Liam
lost three of the cars. So one way we could find out how
many cars Liam has left is to subtract the three that he lost from the nine he had
to begin with.
This is where the 10 frame becomes
really useful. There are nine cars in the 10
frame, and three of them have been crossed out because we know that Liam lost three
of his cars. How many cars are there left? In other words, what is nine take
away three? It’s six. There are six cars left in the 10
frame, so we know that three and six are the two numbers that go together to make
nine. If nine take away three is six,
then three plus six equals nine because three and six are a pair of numbers which go
together to make nine. If Liam had nine toy cars and he
lost three of them, he has six cars left.