• 3 months ago
Transcript
00:00Hello kids, welcome to the Dodgeball Gym. Today we will be learning about subtraction
00:07in word problems. We have some fun stuff to learn, so let's get started.
00:14Does anybody know what this sign means when we see it in a math problem?
00:19This sign means to subtract, and some other words for subtract are to take away or minus.
00:25Today we are working with word problems which are just stories about math. Here is our first
00:30word problem. It says, I have seven balloons and then two of them pop. How many balloons
00:36do I have now? Remember, it is good to read it a second time. I have seven balloons and
00:43then two of them pop. How many balloons do I have now?
00:49I believe that this math problem is asking us to take away because it said that they
00:53had seven balloons, but some of them popped. If a balloon pops, you no longer can play
00:58with that balloon, so they go away. So we will be taking two of them away just like
01:02it says in the word problem. I am going to start this with a circle drawing.
01:08Circle drawings are a great way to illustrate math stories or word problems. I am going
01:12to use seven circles to represent the seven balloons that we started with.
01:19Here are the seven balloons. The problem says that two of them popped. Do you think
01:23this means that it will take away two balloons or add two balloons?
01:29We will take away two balloons because they popped. I will put an X on two of these balloons
01:34to show that those two went away. Now the rest of the circles that do not have
01:40an X are the balloons that I have left. This is an awesome way to figure out the math problem.
01:46We need to write an equation to go along with this word problem.
01:51If you remember we had seven balloons total at the beginning, so we will write the total
01:55or seven first because this is how many we had before any of them popped.
02:00Then it told us that two of those balloons popped. We will now use the minus sign or
02:05the take away sign, which tells me that I am going to take away two of those balloons
02:08that popped. When we take the two balloons away, how many
02:13do we have left? Looking at the circles we started with seven
02:18and two popped and that leaves us with one, two, three, four, five. We have five balloons
02:24left. Great job kids, you guys are awesome! Let's quickly do a math mountain even though
02:31we have figured out the word problem. The really cool part about subtraction problems
02:36with math mountains is that usually we know the total. In this problem the total we started
02:41with is seven. This seven is at the top because it is the total we started with. I also know
02:47that of those seven balloons two of them popped. The two goes down as one of the partners.
02:53How many are left after the two balloons popped? The empty box is where the answer will go
03:00and it will be how many balloons are left after two balloons popped. We know it's five
03:04because we counted in our circle drawing and there are five balloons left. We can check
03:09our work with the math mountain because we know that two plus the other partner five
03:13equals seven which is the total. Awesome kids! Let's do another problem and see if you can
03:19do it. This time we are going to start by writing a math mountain, an equation and then
03:24a circle drawing to prove the answer. Here is another word problem. It says eight children
03:30are playing then five have to go home. How many are still playing? Let's read this one
03:35more time. Eight children are playing then five have to go home. How many are still playing?
03:44Let's start with a math mountain. I will give you a moment to do it yourself, okay? I can
03:52tell just by reading this problem that I have a total because eight children were playing
03:56and some had to go home. So our total is eight which goes at the top of the math mountain.
04:02We also know that five of the children had to go home. Five is one of the partners. We
04:08need to find out how many of those eight children are still playing after five went home. As
04:14we can see we have a total and we have one of our partners. We need to find out the other
04:18partner. With this information we can now write an equation. What is the equation? We
04:27have eight kids that were playing so we will write our total first because all good subtraction
04:31problems start with the total. Then I will put down the subtraction sign. Five of them
04:37had to go home so we put down five. And now there are still some playing but we do not
04:44know how many that is. What is eight take away five? The answer is three. Eight subtract
04:53five is three. Amazing job kids! To check our work we can use a circle drawing. Here
05:00we have eight circles to show the total amount of kids we started with. Now we subtract five
05:05circles because five of the kids went home. This leaves us with three circles which proves
05:11our answer. You guys did an awesome job! Thank you for helping me. We will see you next time.
05:18Goodbye!