(quirky music) - [Kids] Math Mights!

- Welcome second grade Math Mights.

I'm so excited that you've joined us today!

My name is Mrs. McCartney, and we are going to have so much fun with math.

Let's check out our plan for the show today.

Today, we're going to do a mystery math mistake and measure with inches and feet.

Oh no!

What's happened to all of our friends in Mathville?

I could see that DC is holding Abracus's wand!

Well, here's how a mystery math mistake works.

It's going to be your job to listen to how one of our Math Mights solved a problem.

You're going to be a detective and look very closely to see if you can find out where the mystery math mistake is.

We want to be able to help set our Math Might friends straight.

Let's see who is going to show us the problem that they're struggling with.

It looks like it's my friend Value Pak.

They're trying to solve the problem, 56 plus 37 equals 83.

It looks like they tried solving this with their strategy called partial sums.

Let me show you how they told me they solved it to see if you can find the mystery math mistake.

Here, they looked at the number of 56 and they decomposed it into 50 and 6.

For the number of 37, they decompose it into 30 and 7, adding up their partial sums.

They started to add 50 plus 30, which equals 80, and then added the 6 plus 7 to get 13, to get their answer of 83.

83, is that the correct answer?

Do you think you spotted a mystery math mistake?

Let's see what some of our friends are thinking.

Our friend Landon says, well, I think Value Pak decomposed both 56 and 37 correctly.

If we look down here, it looks like Landon is onto something.

He did decompose 56 into 50 and 6, and then they decompose 37 into 30 and 7.

I don't think we found the mystery math mistake yet.

Let's see what our other friends are thinking.

Here, we have our friend Ryan and he says, it looks like when Value Pak was adding 80 plus 13.

He only added the 3 in 13.

It should be 80 plus 13 equals 93.

I want to take a look at that.

I think I know what he's saying, 80 plus three, equals 83, but Value Pak forgot that this value here is 13.

So 80 plus 10 is 90, plus 3 more is 93.

There was a computation error while Value Pak was adding in those partial sums.

So we now know that 56 plus 37 equals 93.

Awesome job helping us find that mystery math mistake.

You know, you're getting good at these strategies when you can find an error and figure out how to solve it correctly.

I know that Value Pak would be very happy with our help.

Let's check out our "I can" statement of the day.

Our "I can" statement says, I can measure longer lengths with feet and inches.

I want you to take a look at Cobia's fish.

Cobia is the boy standing in the picture.

On the left side, you see a fish that's hanging.

That is the length of Cobias fish.

Do you think you can figure out how long Cobia's fish is?

Let's give you a little bit more details.

How about if I told you that Cobia is 48 inches tall?

If I kinda thought about that, 48 inches, could you make an estimate to tell me about how tall or long his fish is?

Let's see what the boys think.

Landon says, I think a too low estimate would be 50 inches, because that is not much taller than Cobia.

If I'm looking at Cobia and we know that it said that he was 48 inches tall, that wouldn't be much taller than what he is there.

So I think I would agree with Landon that that is a little bit too low of an estimate.

Our friend Ryan says, I think a too high estimate would be 96, inches because it's double the height of Cobia.

96 inches would be taking his 48 and then another 48, which would be much taller than the fish.

What are you thinking, that would be a just about right estimate?

The hard thing about this picture is the way the placement of the fish is.

Let's take a look.

I see a shadow here.

So it's almost like I could push Cobia up and would be level or even with where the fish length is.

Cause the fish isn't really on the floor.

So if Cobia is 48 inches tall, what might be a good estimate?

We know that a good estimate might be that the fish is about 60 to 70 inches long.

Remember an estimate is just using the reason of what you know about measuring with inches, to give you an idea.

We would obviously have to measure the length of the fish and then compare it with Cobia, to make that firm decision as to how much taller the fish is, than Cobia.

Let's see what our friend Landon is thinking.

He decided to measure the spiny dogfish shark.

He says that he measured and it was 48 inches.

Our job today is to figure out how many feet is the spiny dogfish shark?

So let's take a look first here.

I have the length in inches.

I'm going to go ahead and record that Landon thought it was 48 inches.

Now, the question I have for you, boys and girls is how many inches are there in a foot?

We certainly have to know that conversion, in order to take the 48 inches and figure out how many feet there are.

Here, I have a ruler.

On one side it has centimeters, the other side has inches.

This length of this ruler is one foot.

Our measurement for our one foot is 12 inches long.

So, I want you to picture if I had to measure something and it was 48 inches, I would probably measuring with a larger yardstick or something larger that I could measure with.

I want you to think about how can we put some of our mathematical ideas into place to see if we can figure out how many feet there are in 48 inches.

So, I'm going to kind of put this up here.

We know that 12 inches, equals one foot.

This is the abbreviation for foot, F T period.

Knowing this conversion, I think it might be a great idea if we count up by 12, until we get to 48 to see how many feet there are in 48 inches.

If I did 12 plus 12, I know that 10 plus 10 equals 20 and 2 plus 2 equals 4.

So what I'm going to do with my red marker is put a box around here to say that that's one foot, then I have two feet, and then I'm going to keep going.

I'm going to take my 24 and add another 12.

I know that 20 plus 10 is 30, and 4 plus 2 is 6.

We went ahead and added on another foot.

I know if we're at 36, we're not quite to 48.

So let's add on 12 more inches.

36 plus 12, I know that 30 plus 10 gives me 40 and 6 plus 2 gives me 8.

I'm going to go ahead and put a square around this to show that I have another foot.

We finally got to our 48.

So we have 1, 2, 3, 4 feet.

We know that when Landon was measuring the spiny dogfish shark, it, the length of it was actually four feet.

Does that conversion measurement makes sense to you?

It's a little bit harder, but you have to think of the idea of skip counting like you would by tens.

But instead we kept adding on 12, counting how many feet we were going to get to those inches.

Let's check out the one that Ryan was looking at.

Our friend, Ryan decided to measure the catfish.

He figured out the length in inches is 36 inches.

It's our job to figure out how many feet long is this?

Let's go ahead and write in the inches.

The length in inches for his catfish is 36 inches.

I want you to think about this.

How many inches are there in one foot?

We know that there's 12.

So let's start with 12, and keep counting on until we get to 36.

So I have 12 plus 12, which we know equals 10 plus 10 is 20, 2 plus 2 equals 4.

We're going to go ahead this time in square out how many feet we have.

One foot, two foot.

We're not quite there, we need to get to 36.

So we have our 24 plus 12 more, 20 plus 10 is 30, 4 plus 2 is 6.

We got to that number, 36.

We're trying to figure out how many feet are there in 36 inches.

1, 2, 3 feet are in the 36 inches.

Great job measuring the fish and really figuring out how to convert the inches to feet.

It's a really great skill to understand.

We had kids figure out the feet for the inches for all the other fish.

I brought three of them here for you to take a closer look at.

Why are our measurements in feet so much smaller than our measurements in inches?

With what you know about measurement, why is that?

Why would those numbers not be closer together?

They're quite far apart.

If I look here 4 and 48 is a really big difference.

And so is 3 and 36.

It goes back to the idea when we're looking at a ruler that an inch is this large.

When we look at a foot it's much longer.

And so when we, of course, when we see something, we would want to know that the feet would be smaller as far as the number, because it's counting this entire piece, where the inches is just counting these small little sections in between.

I'm wondering if we can relate this knowledge to decide in the real world, if you were measuring things, would I measure in inches, or would I measure in feet?

We're going to have objects that we look at and decide if we should measure it in inches or in feet.

Let's start off with a glue stick.

Here, I have a glue stick.

Do you think we should measure it in inches or in feet?

Now, remember, I don't think I've ever seen a glue stick that is this long, which that would be at least a foot.

What are you thinking?

You're right.

We would measure a glue stick in inches.

Now, if we were to think about trying to measure a student's desk, think of your desk at school, do you think we would measure it in inches or in feet?

Well, a desk is quite long, I think it would take a while to count all those little inches.

Not that you couldn't do it, but if you guessed feet, you're correct.

Let's highlight that.

Now I want you to think about 24 connecting cubes.

This here is one connecting cube, if I were to stack 24 of these, do you think you would measure it in feet or in inches?

If you guessed feet, you're correct.

I know that these are about one inch.

So if I had 24 of them, they're going to be about two feet.

Our last item is to think about a pencil.

Do you think that you would measure a pencil in inches or in feet?

It would be a really tall pencil if you're going to measure it in feet.

If you guessed inches, you're right.

It's really important when we're learning about measurement in second grade, to really think about what we're learning about and how it relates to your life.

It's your turn to show your understanding of inches and feet.

You're going to get to explain your reasoning, to decide if something should be measured in inches or feet, like we did today.

Second grade Math Mights, I've had such a great time hanging out with you today.

We really discovered an error there, in the partial sums with Value Pak.

And then we learned a lot about inches and feet, even though we can measure things in inches, we want to think about maybe it's a little bit more efficient to measure something in feet.

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

(outro) (quirky music) - [Child] SIS4teachers.org changing the way you think about math.

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