The snake is five times as long as
the caterpillar. Pick the model that shows how long
the snake is.
In this question, we’re being asked
to compare two things, the length of the snake and the length of the
caterpillar. And we’re going to need to use
multiplication to solve this problem. We know this because the question
tells us the snake is five times as long as the caterpillar. When we compare two things using
multiplication, we call this a multiplicative comparison problem. We have to use multiplication to
calculate how long the snake is.
When we’re trying to solve
multiplicative comparison problems like this, it helps to sketch a bar model. We’re not told how long the
caterpillar is. We could use this bar to represent
the caterpillar. And we know the snake is five times
longer than this. So, the bar representing the length
of the snake would look like this: five times the length is the bar representing the
Now, we have to pick the model
which shows how long the snake is. Let’s look closely at the first
model. Did you notice that this cube train
has been made using groups of three cubes? How many groups of three are
there? One, two, three, four, five, five
groups of three or three multiplied by five. So, if the caterpillar is three
cubes long, then each of the bars would be worth three cubes. And the length of the snake would
be five lots of three. So, this is the model that shows
how long the snake is.
If the length of the caterpillar is
one times three, the length of the snake must be five times three. This model shows three plus five,
not three times five. And this model shows two plus
three, which equals five. We picked the model which is five
times as long as the caterpillar.