Representing one step word problems

- [Instructor] We're told
that Jamal has 324 marbles

in his collection.

His brother Mateo has 198
more marbles than Jamal.

Which strip diagram can be used

to find out how many marbles Mateo has?

So, pause this video and think
about which choice you think

is going to be used to find
out how many marbles Mateo has.

All right, now let's do this together.

So, this first strip diagram,

it's starting with 324,

and then it's adding another 198

to find what 324 plus
198 would be equal to.

Now, this is actually making sense,

because if we say Jamal has 324 marbles,

so this right over here is
represented by this strip,

the 324 that Jamal has.

And then when we say the brother has,

or Mateo has 198 more,

so now we're increasing it by 198.

So, Mateo would have this
purple right over here.

So, this is what Mateo is going to have,

198 more than 324.

So, I like this choice,

but let's just make sure

that this other choice doesn't make sense.

So, here, we have 198.

We're essentially asking,

"What do we need to add
to 198 to get to 324?"

But we're not trying to get to 324.

We're starting with 324

and then we're trying to get to a number

that's 198 more to figure
out how many Mateo has.

So, yes, I like choice A.

Let's do another one, but this time,

let's use number line, or number lines.

A theater has 642 seats.

During the show, 357 seats were filled.

Which number line can be used to find out

how many seats were empty in the theater?

Once again, pause this video,

try this on your own
before we do this together.

Okay, so this first one, choice A,

it looks like in blue
we are starting with,

it looks like this arrow
goes from zero to 642.

I'm guessing this is 642 right over here.

So, that's the 642 seats,

and then it looks like it's
subtracting, I don't know,

it looks like it's
subtracting about 100, 200.

It looks like it's subtracting
something to get to 357.

This looks like this right, let
me do this in another color.

So, 357 is right around here.

So, it looks like they're
subtracting some amount,

some amount, I'll do
that same brown color,

some amount to get to 357.

And that would be the
number of empty seats.

However much you have to
take from 642 to get to 357,

this right over here is
the number of empty seats.

So, this one might be useful.

Let's look at the other choice.

This one starts at the 642, it looks like,

and then it looks like
it's adding 357 to that.

Well, that's not what we're talking about.

It's not that these 357 were
filled on top of the 642,

it's that 357 of the 642 are filled,

and then there's some amount
that is empty over here.

So, if we could figure out
how much we have to go back

from 642 to get to 357,

then that would tell us
the number of empty seats.

And so, I like choice A.