Video Transcript
There are six apples. Some are red and others are
green. Two of them are red. How many green apples are
there?
This word problem is all about
a group. We’re told that this is a group
of six apples. Some are red and others are
green. But we don’t know to start with
how many red and how many green apples there are. And that’s why in the first
picture we can see six apples, but they haven’t been colored yet. At the moment, they’re all in
shadow. And in our second sentence,
we’re told a fact about our group of apples. We’re told that two of them are
red. Because the apples are either
red or green, we can also say that the rest are going to be green.
Now, the word problem asks us,
how many green apples are there? You know, we can represent this
problem using a part–whole model. There are six apples
altogether, so we can say that the whole amount is six. Now, we can break up the number
six into two parts: one representing red apples and one representing green
apples. So let’s color-code our
part–whole model.
We know that two of the apples
are red. And we don’t know how many
green apples there are. This is the part we need to
find. To find our missing part, we
could start with the whole amount, which is six, and take away the part that we
know, which is two. Six apples take away two apples
leaves us with how many apples?
Let’s model the problem using
counters. We’ll start with six
counters. We can take away two
counters. And this leaves us with one,
two, three, four counters. The number six can be broken
apart into a group of two and a group of four because two and four go together
to make six. If there are six apples — some
are red; others are green — and we know that two of the apples are red, then we
can say that the number of green apples is four.