(upbeat music) - [Children] Math Mights!

- Hey Math Mights, welcome back.

And if it's your first time, I'm Mrs. Markavich.

And I'm so excited that you're here with me today.

Let's check out our plan for the day.

Today, we're going to solve a Mystery Math Mistake, and we'll indirectly compare objects.

Let's warm up our math brain with a Mystery Math Mistake.

Oh no.

All of our Math Mights got their strategies all mixed up.

And I need your help to see if we can solve the Mystery Math Mistake.

Here's how it works.

I'm going to act out a problem with a concept that you're already familiar with, and you're going to use your magnifying glass to see if you can figure out my mistake.

Not a real magnifying glass, one that looks like this.

You can make it with your hand, and you can be a Math Detective.

And then I want you to be able to make sure you can explain your reasoning.

I've got the problem written out for us here, 25 plus 36.

And look who's here to help us.

But, look at him.

He's upside down and sideways.

That's our friend Value Pak.

And remember he got his strategies all mixed up.

Remember Value Pak, he wears this value on his belly, and when he clicks apart, we can see the tens and the ones.

Let's see if we can help Value Pak figure out where he got all mixed up at.

First, I'm going to decompose the 25, into 20 and five.

Then I'm going to decompose the 36, into 30 and six.

I'm going to add the tens and get 50, add the ones and get 11.

And then I know that 50 plus 11 equals 51.

So I think that 25 plus 36 equals 51.

But, my friend Dennis says, "I know "25 and 25 is 50.

"I wonder how when you add 25 plus 36, "it could only be one more than 50."

And Huan says, "I think you added incorrectly.

"50 plus 11 is 61.

"Not 51."

Good thinking Huan.

I wonder if you were able to find the mistake, like Huan did.

Let's have Value Pak correct that now.

Hey Value Pak.

You're all straightened up now, and back together.

Let's see if we can figure out where that mistake was made.

We added the 20 and 30 and got 50.

That was correct.

We added the five and the six, and that was correct.

But right down here where we did our addition problem, that's where our mistake was.

We need to erase this part and just add this correctly.

50 plus 11 equals 61.

Thanks for finding that mistake, and paying such great attention to detail Huan.

Now, let's check out our I can statement of the day.

Our I can statement of the day says, "I can use a third object to find longer "and shorter objects."

Let's take a look at these pencils.

What do you notice?

What do you wonder?

Well, when I look at these pencils, I see four pencils on the paper.

Two of the pencils are the same.

And then there are two other pencils that are a different color.

I wonder what they're trying to do?

Let's see what our friends Dennis and Huan have to say.

Dennis says, "I noticed the pencils are different lengths."

And Huan says, "I noticed the pencils "are lined up by their end point."

Dennis says, "I wonder which pencil is the longest?"

And Huan says, "I wonder which pencil is the shortest?"

Wow boys, those were really great notices and wonders.

Let's take a closer look at our pencils.

Which pencil is the longest?

Pencil A or pencil C?

How do you know?

Huan says, "A is longer than B "and C is shorter than B.

"So C is shorter than A" Wow, that was a lot of words.

I think we need to take a look at the overhead to make sense of what Huan was saying.

Let's check it out.

You can see here.

I have pencil A, pencil B, and then I have pencil B again and pencil C. The first thing we're doing is comparing pencil A to pencil B.

And you can see pencil A is longer than pencil B.

Then, Huan said, "Pencil C is shorter than pencil B."

So we actually just moved pencil B down here, to make the comparison between these two pencils.

And you can see that pencil C is shorter than pencil B.

So after taking a closer look, I think I can come to the conclusion that pencil C is shorter than pencil A.

We can see that pencil C is shorter than pencil A.

That was a lot of great work, first grade Math Mights.

It's really great when you can use the Math language to talk about things like shorter than, and longer than.

It would be fun to measure objects with yarn.

Think about where you're at right now.

Maybe you're at school.

Do you think you could measure your desk?

You could the height and the length of your desk.

I don't have a desk with me right now, but I do have my whiteboard.

So we're going to use some yarn and measure my whiteboard.

We're going to measure the length and the width.

I'm gonna take my string, and start at the end point.

And then I'm gonna go all the way to the other end point.

I'm gonna grab my scissors, and cut it as closely as I can to the other end point.

I don't need this piece anymore.

Now, I'm going to turn my whiteboard to measure the width.

Wow, look at that.

Can you see how much longer my string is?

Well that was fun.

I was able to tell that the width of the whiteboard was longer than the length of the whiteboard.

How was using the yarn helpful in comparing lengths?

Huan says, "You could put the yarn next to each side "of the dry erase board to see which side was longer."

Great thinking Huan.

That was a great way to explain comparing the lengths.

Now I wanna talk about how you get to school.

Think about some ways that you could get to school.

You could take the bus, you could have an adult drive you every day, or you could even walk to school.

Let's talk about my friends, Claire and Mai.

They walk to school every day.

We want to figure out who has the shorter walk.

Well I happeN to have that here in front of me.

And you can see that I have Claire's house, school, Mai's house and school.

I'm wondering since I can't move the two lines on the paper, if I could use yarn to see how far it is from Mai's house to school and from Claire's house to school.

The first thing I'm gonna do is start at Claire's house.

I'm gonna take my string, and put it at the end point.

Remember, we always have to measure from end point to end point.

I'm gonna cut the string right there.

I'll put the extra piece aside.

Then, I'm going to take a piece of purple string, and measure from Mai's house to school.

I've lined it up very carefully at the end point, and I measured from end point to end point.

I'll put this piece aside as well.

Then, I can take the two pieces and move them.

And if I line them up at their end points, what do you notice?

I noticed that Claire's walk is longer than Mai's walk.

So I know that Mai has the shorter walk to school.

But guess what?

I can try it one more way.

I have another piece of string.

I'm gonna move these two pieces out of the way.

And I'm going to take my new piece.

I'm going to start at Claire's house.

And really you could pick either line to start at, I'm just choosing to start at Claire's house.

Line it up from end point to end point, cut the string, move that extra part aside so that it doesn't get in our way.

You can see here is the distance from Claire's house to school.

I can take the same piece of string, move it over to Mai's house and look what you can see.

Look at how long the string is.

It goes way past the end point.

So you can see that the shorter walk is from Mai's house to school.

How was using a tool helpful to compare the lengths of the path?

Dennis says, "We couldn't put the lines "next to each other at the end points, "so the tool, which was the yarn helped."

That was really fun.

I was able to use the string to find two ways to find out who has the shorter walk to school.

I hope you had fun trying this.

Can you use the word highlighter and pencil to complete the sentence?

The hm is longer than the hm.

Well I happen to have that in front of me.

Let's take a closer look at it.

You can see that I have a pencil, a highlighter, and a pen.

When we're being Math Detectives, we have to look for information that we need.

And I never heard them ask us about that pen.

So we're going to kind of ignore that pen.

We're only comparing the pencil to the highlighter.

The next thing is, I can't actually pick them up.

There on the paper, so I can't move them.

I have to indirectly compare them.

Which means I have to use my eyes and look to see which one is longer.

And just by looking at it, I can say that the highlighter is longer than the pencil.

So I'm going to write that in on my sentence at the bottom.

The highlighter is longer than the pencil.

Were you thinking the same thing?

Were you thinking that the highlighter was longer than the pencil?

I think we can do one more thing.

Remember when we used the yarn to compare the distance from Mai's house to school, and Claire's house to school?

Let's try that now.

I'm going to start with my purple piece of yarn.

I'm gonna line it up at the end points.

So here's the end point of the marker, and I wanna go all the way to that tippy top point of that highlighter, right there.

I'm gonna move that piece aside so I don't get confused.

Now, when I take it here and go like this, you can see the length of the highlighter.

I can move the yarn over to the pencil.

Wow, when I started at the end point, look how much longer the yarn is than the pencil.

So my statement down here, the highlighter is longer than the pencil is still accurate.

Great measuring.

But I think I wanna try one more thing.

I feel really bad for that pen.

He feels left out.

So let's use two more pieces of yarn, and compare all three writing utensils.

So I'm going to take three different colored pieces of yarn, and measure each object.

I still have my piece of yarn that I used to measure the highlighter.

So I'm going to keep that there.

I'm going to grab another piece of yarn to measure my pencil.

Remember, we're going to measure from end point to end point.

I'm going to take it and cut it very carefully, almost like you're a doctor in surgery.

Line that up.

Then, I have one more object to measure, the pen.

And I just happen to have one more piece of yarn right here.

We're gonna go from endpoint to endpoint.

I'm gonna use my scissors and very carefully cut that.

Just like that.

Now, you're probably thinking, "Well, what do I do now?"

Remember before, when we talked about lining them up from end point to end point?

I'm gonna move the yarn and see if I can line them all up to see which one is longer.

So I have the pencil and the pen, and you can see when they're lined up, end point to end point, the pen is longer than the pencil.

Let's not forget about the highlighter.

If I drag that over and line it up at the end point, you can see that the highlighter is longer than the pen, and the highlighter is longer than the pencil.

So I can take what I know and add it in my sentence.

The highlighter is longer than the pen and the pencil.

Excellent work Math Mights.

That was so much fun.

Indirectly comparing the lengths of the objects and using the tool, the yarn, to compare all three objects.

Hey Math Mights, now it's your turn.

It's time for you to compare objects with yarn or string.

Great job today Math Mights.

I had so much fun with you.

We started out our day by solving a Mystery Math Mistake.

Remember, all of our Math Mights got their strategies all mixed up, but Value Pak was able to come through in the end.

And then we were able to indirectly compare objects by using yarn.

I think you definitely need to kiss your brains.

(upbeat music) (upbeat music) - [Child Voiceover] Sis4teachers.org.

Changing the way you think about Math.

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