Representing one-step word problems
About this video
This video shows how to pick a strip diagram or number line that matches a one-step word problem. When Mateo has 198 more marbles than Jamal's 324, we add. When 357 of 642 theater seats are filled, we find the empty seats by going back from 642 to 357.
You'll be able to
- choose a strip diagram that shows a "more than" word problem.
- choose a number line that shows how many are left or empty.
- explain why a diagram does not match a word problem.
Key words
- strip diagram
- A drawing made of bars (strips) that shows how amounts in a problem fit together.
- number line
- A line with numbers in order; arrows can show adding (moving right) or subtracting (moving left).
- more than
- A clue that one amount is bigger, so you add to the first amount.
Transcript
- [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.
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