(lively music) (metal clinking sound) - [Children] Math Might.

- Welcome 2nd Grade Math Mights, I'm so excited that you've joined us for our Math Might Show.

My name is Mrs. McCartney, and we have a great show planned for you today.

Let's check out our plan for today.

Today we're gonna be doing a mystery math mistake, and then we're gonna be measuring with inches.

Let's start off first by warming up our brain with a mystery math mistake.

Oh no, look at all of our math might characters, they look like they've gotten stuck in a cyclone and all of their strategies are mixed up.

Why is DC holding Abracus's wand and T-pops holding DC's mallet?

Well, here's how the mystery math mistake works, the mystery math mistake works where a character is going to share their strategy with us.

It's your job to be a detective and look closely at the math strategy to see if you can find the mystery math mistake.

Let's see which one of our friends from Mathville is needing some help.

Oh no, it's our friend Value Pak, they're upside down and all turned around.

It looks like they were trying to solve 43 plus 56.

They have the answer of 89.

Let's work through how Value Pak told me that they solved the problem to see if you can detect the mystery math mistake.

Here we have our problem of 43 plus 56 equals 89.

The Value Pak decided to decompose the number 43 into 40 and 3.

Then they took the number 56 and decomposed it into 50 and 6.

They use the strategy of partial sum.

So let's see how they put it together.

Here they added 40 plus 50 to get 80 and then three plus six to get nine, putting that together to get the total of 89.

Did you use your magnifying glass to find that mystery math mistake?

Do you see where we can help out Value Pak?

Let's see what my friend Sunshine is thinking.

She says, "I think Value Pak decomposed both 43 and 56 correctly."

Here, if we look at what Sunshine's talking about, I think she's right.

Value Pak decomposed 43 into 40 and 3 and 56 into 50 and 6.

So that cannot be where the error is.

Let's see what Mariah is thinking.

She said, "It looks like when Value Pak was adding 40 plus 50, they thought it was 80, but it should be 90.

So the answer should be 99 not 89."

Oh, I think Mariah maybe has found our mystery math mistake.

Let's check it out.

When Value Pak was adding 40 plus 50, they did put 80.

That's not correct.

So I'm gonna go ahead and cross this off.

40 plus 50 does equal 90, six and three equals nine.

So that would make the answer 99, not 89.

Great catch Mariah, did you catch that too?

We know we're great mathematicians when you can discover a math mistakes and figure out how they can be corrected.

Let's check out our "I Can" Statement of the day.

Our "I Can" Statement says, "I can measure with inches."

I want you to take a look at these rulers, one at the top and one at the bottom with a centimeter cube in the middle.

What do you notice?

What do you wonder?

I'm wondering about the two different rulers that we're looking at.

Did you notice anything or are you wondering anything?

Our friends are looking at this having some wonders.

when I'm looking at those rulers, I think I have a lot of notices and maybe a few wonders.

Those rulers look similar, but I'm not quite certain.

Let's see what Sunshine and Mariah are thinking.

Our friend Sunshine notices that they are both rulers.

They are both labeled starting at zero.

Mariah says, "The centimeter cube lines up with the top ruler from zero to one but not the other."

These are both really great notices from the girls.

Let's see if we can take a closer look.

I definitely agree with Sunshine that both of these rulers have a starting point of zero.

But when Mariah was looking at the centimeter cube, she had a great notice, she said that the top ruler, it goes from zero to one, looking at the length of it.

But when she came down here, it certainly did not make it all the way to the one.

Those are great notices.

Let's see what they're wondering.

Sunshine says, "Why is the spacing different?

What unit is it?"

Mariah says, "I wonder if it's an inch ruler."

These are both really great wonders.

If I look at the ruler here, I am wondering, "Why is the spacing from zero to one different than the spacing on this ruler?

What is this unit called?"

Our friend Mariah is wondering if this is an inch ruler.

What do you think?

Let's take a closer look at a ruler that has inches in it to see if we can discover that.

Here I have the ruler that we were talking about.

I'm gonna use this one inch square tile to decide if it is one inch.

I'm gonna lay it in between the zero and one.

Look at that, this is a one inch ruler.

This is our customary measurement that we use in the United States to measure.

This ruler here has a total of nine inches in it.

Do you think you can find two items that are at least one inch long?

Do you think you can find something where you are that is at least one inch long?

Remember, as you're thinking about this, this is about one inch long.

I have a couple things that I found here that are about one inch long.

Let's check it out.

I have my one inch square tile, I know that is how it matched on my ruler, so if I was kind of estimating, I think my Springling pencil topper is about one inch.

The other item that I found near me was a quarter, a quarter is about one inch.

Now that we have a good understanding of how long an inch is, let's see if we can measure.

I have a chart here where we're going to use our one inch ruler to measure some objects.

We're gonna measure a marker, a colored pencil, some connecting cubes and a book.

Let's start off first with our marker.

I have my ruler and my marker.

I'm gonna line it up to the zero inch and look to see how long it is.

It looks like our marker endpoint ends at five.

I'm gonna go ahead and put in five and then I'm gonna put 'in.'

which is an abbreviation for inches.

Now that we have our marker, let's try to see how long our colored pencil is.

Here I have my ruler and my colored pencil.

I'm gonna align it up to the zero and hold it to see where it is.

Now, this could happen, second graders, when you're measuring with inches.

We're going to go to the closest inch.

So if I'm looking here and kind of made a mark, this is very close to the six, not to the seven.

So we're gonna put that this is about six inches long.

Let's record that here, '6in.'

Now we have a set of connecting cubes.

I'm gonna push my cubes together, line them up at zero and find out where they end.

This is a close call because it's just a little bit closer to the eight than it is to the seven.

So we're gonna put that as eight inches.

My last object that I'm gonna measure is a book.

Let's take a look at this book with our ruler.

Here I have our Counting Buddy book that we use a lot on the Math Might Show with our Counting Buddy Junior and Senior.

I'm gonna take the book and line it up on the zero and follow it all the way to the end to see that our Counting Buddy book is eight inches long.

It's actually about the same size as our 11 connecting cubes.

That was a great job measuring all those objects.

It's really important when you're measuring with inches, just like we do with centimeters, that we start at zero.

So be careful in school that you're not measuring at the start of the ruler, that you're actually taking the object to the zero and measuring it from end point to end point.

Now I'm wondering if we can apply our knowledge with measuring objects to see if we can measure shapes.

I have a triangle, a rectangle, and a square.

I'm wanting to see if we can measure these objects.

When we start to look at this particular rectangle, we can see that it has four sides.

We know from first grade, when we looked at a rectangle, that all the sides are not equal.

We know the top and the bottom are equal size and the sides in the other side are equal size.

Let's see if we can use that ruler to help us measure this.

We're gonna go ahead and measure this length of the rectangle.

I'm gonna line up the corner here on the zero and follow my ruler all the way down to seven.

It might be just a hair off, but we know that it's closest to seven.

So we know the length of this side of the rectangle is seven inches.

So I'm gonna draw a line here, and put '7in.'

which is short for inches to show the length of this side of the rectangle is seven inches.

Now, if we wanted to measure this side of the rectangle, I'm gonna go ahead and turn my ruler, again, being very careful to line it up at zero and trying to see how far it is.

This is a little bit longer than our one inch, being reminded that this is really blown up to scale, but kinda getting the idea that we're closer to one inch.

So we're gonna say the distance from here to here is one inch.

Now we're gonna start to take a look at the square.

You know that a square has four corners and four sides.

Let's see what we discover.

I'm gonna line up my ruler from the corner of zero to the other corner, looking at the estimate, about of two inches.

I'm gonna label it two inches.

And I think maybe we should measure the other side of the square.

Wait a minute, what do we know about squares?

We know that all of the lengths of the sides are all the same length.

So hopefully when we measure this, this should also be about two inches long, let's double check.

If I turn my ruler this way, yep, it is not quite three, but it's definitely closer to two.

So this whole square is two inches on each of the sides.

Now that we look at this triangle, it looks a little bit different.

There's three different lengths to each of the parts of this triangle.

A triangle is made up of three corners and three sides.

Let's measure the bottom part of the triangle to see about how long it is.

It looks like here it's very close to nine inches.

I'm gonna go ahead and draw my line and put '9in.'

to show the length of that triangle.

When I look at this side of the triangle, it's a little bit shorter.

I'm gonna make sure that you're not lining it up and kind of making a guess, you really wanna make sure that you're lining your ruler up so that you can see where it is.

This one is about, in our blown up scale, about three inches.

Now if I were to measure on this length, I'm gonna start, again, making sure my ruler's lined up, this is really close to about six inches.

So I'm gonna label this side six inches.

Great job measuring the shapes, we were able to look at each of the sides to measure it.

Let's see now if we can use our ruler to measure a stapler from my desk.

I'm gonna go ahead and measure it from end point to end point.

Now, depending on how you're measuring, you wanna make sure you're looking at the full length.

So I'm gonna go ahead and place the ruler here using my fingers from end point to end point and look to see that that's really close to six inches.

So this is actually a stapler that is six inches long.

It's your turn to practice measuring with inches.

You're gonna find items that you can measure to the nearest inch by cutting out your own inch ruler.

Second Grade Math Mights, I've had a great time hanging out with you today from our mystery math mistake to becoming experts with measuring with inches.

I sure hope to see you on another Math Might episode soon.

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