Video Transcript
Taking Apart
In this video, we’re going to learn
how to count to find how many objects are in one part when we break apart a group of
up to 10 objects into two parts.
This boy is a classroom helper. It’s his job to look after all the
pencils on each table in his classroom. And we can also see a pot of 10
pencils. The helper is asking for four
pencils. Let’s give him four pencils. We’ll need to take them out of the
pot. We’ve given out classroom helper
four pencils. How many are left in the pot? Did you count them correctly? There are six pencils left. We had 10 pencils in the pot to
begin with. The class monitor took four pencils
away and there were six pencils left in the pot. When we take objects away from a
group, we’re subtracting. The whole amount or the number of
pencils we had to start with was 10. If we break this number apart by
taking away four, we’ll have six pencils left in the pot. So we can say that 10 take away
four is six.
We could do the same using a cube
train or counting blocks. This cube train has been broken
apart. How many cubes are there
altogether? Let’s count them: one, two, three,
four, five, six, seven, eight, nine. This is the whole amount or the
amount of cubes we used to make our cube train. We can see that the cube train has
been broken apart. Let’s count how many cubes were
taken away: one, two, three, four. We had nine cubes to start with;
this is the whole amount, and we broke the whole amount apart. We took away four cubes. How many are left? Let’s count. There’s one, two, three, four,
five, so we can say nine take away four is five.
In this video, we’re going to
practice answering some questions where we need to break apart a group of up to 10
objects. And we’re going to use part–whole
models and cube trains to help us count how many objects there are in one part. So let’s try some questions
now.
Complete the following. When I take apart nine, I get five
and what.
In this question, we’re shown nine
apples, and we can see that the group of apples has been taken apart to make two
groups. We’re told that one of the parts or
one of the groups has five apples, and we have to work out how many apples are in
the other part. Let’s record what we know using our
part–whole model.
We’re told that there are nine
apples. This is the whole amount. We’re told that once the apples
have been broken apart, one of the part has five apples and we have to work out how
many are in the other part. Let’s count how many apples are in
each part. This part has one, two, three, four
apples. If this part has four apples, then
this part must have five apples. When I take apart nine, I get five
and four.
A cube train has eight cubes. If five of them are red, how many
green cubes are there?
In this question, we’re shown a
cube train with eight cubes. So this is our cube train. And we can see that the cube train
has been broken into two parts. We’re told that five of the cubes
are red, but we’re not told how many green cubes there are. Let’s write this information in our
part–whole model. We know the cube train has eight
cubes, and we know the red part has five cubes. Let’s count how many green cubes
there are. There’s one, two, three. The green part has three cubes. If a cube train has eight cubes and
five of them are red, then three of them must be green.
Chloe has seven dolls. She puts her dolls into two
boxes. Complete the following
sentence. There are three dolls in one box
and what dolls in the other. Are there four, three, or five?
In this question, we’re told that
Chloe has seven dolls and she puts her dolls into two boxes. We’re also told that there are
three dolls in one box, but we’re not told how many dolls are in the other. We have to choose from three
possible answers. Are there four dolls in the other
box, three, or five? Let’s use a part–whole model to
help us think about the problem.
We know Chloe has seven dolls and
there are three in one box, and we’re trying to work out how many dolls there are in
the other box. Let’s use the picture of the seven
dolls to help us. We can cross out the three dolls
that Chloe has already put away in a box. Then we can count the number of
dolls that are left. There’s one, two, three, four. Now we can complete the
sentence. There are three dolls in one box
and four dolls in the other. The missing number is four.
Complete the following
sentence. When I take eight apart, I get
three and what.
This question is all about breaking
apart our cube train. We’re told that our cube train has
eight cubes, and we have to break it apart into two parts. We’re told that one of the parts
has three cubes, so let’s count out our three cubes: one, two, three. Now we can count the number of
cubes in the other part. One, two, three, four, five. Now we can complete the
sentence. When I take eight apart, I get
three and five. The missing number is five.
Choose two numbers to complete the
following sentence. Nine is what and what. And we’re given three numbers to
choose from: three, six, and five.
Our model shows nine circles. Let’s shade three of them. One, two, three. We had nine circles, and we shaded
three of them orange. Let’s count how many circles are
left. One, two, three, four, five,
six. We can complete the sentence. Nine is three and six. The two numbers we needed to
complete the sentence are three and six.
What have we learned in this
video? We have learned how to find how
many objects are in one part when we break apart a group of up to 10 objects into
two parts.
