(jaunty music) (graphic whooshes) (bells chiming) (spring boings) (crank creaking) (window squeaking) - [Children] Math Mights.
- Welcome second grade Math Mights, I'm so happy that you've joined me today.
My name is Mrs McCartney, and we have a ton of great stuff planned in our show today.
Let's check out what we are going to be doing.
We're going to be doing a mystery math mistake, and then we're going to be stewing story problems about length.
Let's warm our brain with our mystery math mistake.
Oh, no!
What's happened to all of our Math Mights?
They look like all their strategies are mixed up and some of them are using the wrong tools.
Well, let's talk about first what do we do when we do a mystery math mistake, a mystery math mistake is when one of our Math Might friends is having some trouble, and it's our job to be able to help them to be detectives to see where they made that mystery math mistake.
We have a friend from Mathville here that looks like they're upside down and all turned around.
It's my good friend Springling.
She's not sure what's going on, but she tried to solve the problem, 56 - 27 = 28.
She used her strategy of hopping up or back on an open number line.
Let me show you exactly how Springling solved this problem so you get an idea of where that mystery math mistake might be.
On the open number line, Springling told me she went ahead and was looking at the distance between 56 and 27.
She decided while she was hopping to come to a friendly number, which was 30.
She knows when she hops, the distance between 27 and 30 is 2.
Then Springling wanted to do a very big hop, like she loves, to go from 30 to 50, which we know is 20.
Next, she decided to go from 50 to 56, which she said was 6.
She added up the total to get 20, 26, 27, 28.
So Springling thinks 56 minus 27 is 28.
Did you see a mystery math mistake in the way that Springling was solving that problem, or do you think she solved it just great?
Let's see what some of our friends are thinking.
Our friend Krisha says, "I think Springling miscounted.
The distance between 27 and 30 is 3, not 2."
Ooh, that was a catch there, Krisha.
Did you notice that as well?
Let's take a look.
She says when you're hopping from 27 to 30, that it is not the distance of 2.
27 to 30, we know is the distance of 3.
Great catch there, Krisha.
Let's see what our other friends are noticing.
Our friend Dawson says, "I agree!
That would change the answer to be 29, not 28."
If I look here and I add 20 + 6, I have 26, plus 3 more definitely makes that answer 29, not 28.
Great catch Krisha and Dawson.
Did you see that same error that Springling made?
I know you're becoming a great mathematician when you can find errors in math and then explain your reasoning as to why you may have had the wrong answer.
Let's check out our I can statement of the day.
Our I can statement says, "I can solve one-step word problems about length."
Take a look at this picture.
I see a ribbon cutting, and then there's a visual model.
What do you notice and what do you wonder?
I want you to think about that ribbon being cut and the visual model to tell me what you think you're noticing.
Let's see what Krisha and Dawson are thinking.
Our friend Krisha says, "A ribbon is being cut.
The diagram and the equation have the same numbers."
Our friend Dawson says, "There is a dash line through part of the diagram."
Let's take a closer look at that diagram to see what their notices are.
I've drawn out the diagram that you were looking at here.
Our friend Krisha says the ribbon was being cut, which we saw that in the picture, and the diagram and the equation have the same numbers.
I see 54 here and I see 16.
Our friend Dawson said the dash line through the part of the diagram, he's noticing that there's this diagram here and there's a kind of a dash line.
I wonder what that might mean.
Let's see what they are wondering about these two images that they were looking at.
Krisha says, "I wonder why there is a ribbon.
Is the ribbon 54 inches."
Our friend Dawson says, "I wonder if the diagram is being cut, just like the ribbon."
Those are really great wonders.
When I'm looking at this total bar, maybe part of the ribbon was being cut.
What do the diagram and the ribbon have in common?
I want you to think about that for a minute.
I saw the ribbon with really big scissors, cutting it.
When I'm looking at this diagram I can see a total length, and maybe that part that was dotted that we were looking at might be taken away.
I see that the total ribbon might've been 54, like we see here, and then this part of the diagram that has dotted was kind of looking as if this got cut off.
And this is they're looking for as to what is left.
54 minus 16 matches this diagram that we see here.
Great job being able to create a visual model or make an understanding to it just like the ribbon is being cut.
In today's show we're really gonna be applying this concept of measurement to real-life stories and solving for them.
Let's check out a little bit more about this ribbon.
In this picture, you see these girls that are from India that are wearing saree dresses.
Sarees are usually worn by women and girls made by wrapping five to seven meters of fabric in a special way.
Many sarees are made from brightly colored silk, which is a soft fabric.
Sometimes when sarees get too small or are worn out, they are cut into strips to make saree ribbons.
Today we're gonna try to use some real-life stories using the idea of this ribbon.
Our friend Priya and her friends are planning to make saree silk ribbon necklaces.
They are problem solving to make sure they get the measurements correct.
Wait a minute, did I hear story problems?
We're going to be using this real-life situation to solve some story problems.
We can't do that without my friend, Professor Barble.
Hey, Professor Barble, can you come help us with these word problems?
Our friend, Professor Barble, loves to solve word problems.
In fact, he tries to help kids remember that we shouldn't guess if we should add or subtract.
Let's see if Professor Barble can help us solve our first story problem.
The story problem says that Priya had a ribbon that was 44 inches long.
She cut off 18 inches.
How long is Priya's ribbon now?
I have a great idea.
I think we should first create the visual model that Professor Barbel would want us to do to make sure we know if we need to add or subtract.
Let's check it out.
Taking a look at our problem, we know that our who or what is the ribbon that we're talking about.
We're gonna go ahead and create a bar.
That bar right now represents the ribbon that Priya cut.
Do we know how long the ribbon is that Priya cut?
I think the word problem told us.
It says that it's 44 inches long.
So at the end of the bar we've labeled that bar 44 inches long.
The next part says that she cut off 18 inches.
Let's show that in our visual model, I'm gonna go ahead and put the 18 in a diagonal slash there so we know that that section there is what was cut.
The question is asking, how long is Priya's ribbon?
We can't forget Professor Barble wants us to put that question mark in.
Let's go ahead and put that in our visual model.
Now we can see here that we have the question mark, and it's labeled left.
I don't know about you, but visual models really help second graders understand what the words are asking.
I wanna take a look at it here and decide should we add or should we subtract?
I have the ribbon, the 44 inches, imagine that ribbon, and she cut this right here at the 18 inches.
It wants to know how much is left.
Let's see if we could write an equation to go along with this.
I know Priya started off with 44 inches and then she took away 18 inches by cutting it.
We want to know how many inches are left.
Well, I love one of our characters from Mathville to do a problem like this in second grade.
It's my friend's Springling.
Hey, Springling, can you come help us solve this problem?
I have my friend Springling right here.
Springling was born with fancy eyelashes and fluffy fur, and she has this amazing coily tail.
She loves to hop on the open number line to find the distance between two numbers.
She uses it with subtraction on an open number line.
Let's see if we can solve this problem with her.
Our friends Springling wants us to draw an open number line where we start at 18 inches and we end at 44 inches.
A friendly number that she might come to if she's at 18, might be 20, so we're gonna go ahead and hop 2.
Now I'm at the 20, Springling could stop at 30, but we're gonna keep going all the way to 40, because as second graders we know that's the distance of 20.
Last, she's gonna go from the 40 to the 44 to see that the distance here is 4.
When she adds that together, 20 + 4 + 2, that tells us the answer of 26.
You can always check this by looking at 26 + 18 should give us the original length of Priya's ribbon, which was 44 inches.
So we now know that Priya has 26 inches of the ribbon left.
Great job solving that problem with Priya's ribbon.
Using Professor Barble's process with this, even when we're doing measurement, is a great way to help us understand what the word problem's asking.
Let's check out our next problem.
This problem says Han had a piece of ribbon that was 64 inches long.
He cut off 28 inches to make a necklace for his sister.
How much ribbon does he have left?
When we're looking at this, we wanna create that visual model together.
Of course, we know we can start with the who or what to show that we have the ribbon.
Next, we're gonna go ahead and put in our bar.
That bar that we have is going to represent the ribbon.
Han's ribbon was 64 inches long.
Next it says that 28 of the inches were cut.
So on this part of the visual model, we're labeling how many are cut?
The last part tells us how many are left to make sure we put in the question mark to see what we're solving for.
I want you to take a look at the visual model down here so we can get a better picture of how we should solve this.
The ribbon was 64, we took away 28.
We have to solve for how many is left.
We can go ahead and write that number sentence.
64 minus 28 equals blank inches left.
We created a subtraction equation for this problem because it didn't say that Han got more ribbon.
He had a piece of ribbon that he cut, therefore it was taken away so we know that that's subtraction.
Let's try to use Springling's strategy to help us solve this problem.
We're gonna start at 28 and find that distance between these two numbers to tell us what the difference is.
We can go from 28 and stop at 30, which is a friendly number.
When our friends Springling makes that hop, we know that it's 2.
Do you think you could go from 30 all the way to 60?
If you're not comfortable yet doing that on a number line, you can hop with each 10, I'm gonna let sprinkling soar all the way to the 60.
Here we go with the 60 here and she is going to make a giant hop, knowing the distance between 30 and 60 is 30.
Last, from 60 to 64, we know that it's 4.
When we add these together, we have 30 + 4, which is 34, 35, 36.
We know that if we to put the other part of the ribbon, which is the 36 inches, added it to the 28 inches, we would get the total of 64 inches.
Now it's your turn to solve word problems with measurement using Professor Barble's process.
Second grade Math Mights, we have a great time today from our mystery math mistake to applying all of our measurement knowledge and word problems with real-life situations.
I can't wait to see you on another Math Might episode soon.
(jaunty music) (graphic whooshes) (bright upbeat music) (jaunty music) - [Boy] Sis4teachers.org.
(graphic whooshes) - [Girl] Changing the way you think about math.
- [Narrator] The Michigan Learning Channel is made possible with funding from the Michigan Department of Education, the state of Michigan, and by viewers like you.
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