(playful music) - [Children] - Math Mights!

- Welcome Math Mights, I'm Mrs. Markavich, and I'm so excited that you're here with me today.

I have so many great math activities that I know you're going to love.

Speaking of math activities, let's check out our plan for the day.

Today, we'll be doing a mystery math mistake and we'll add and subtract within 20.

Let's warm up our math brain with a mystery math mistake.

Oh no!

All of our math mights have gotten their strategies all mixed up.

What are we going to do?

Okay, well here's how the mystery math mistake is going to work.

One of our math might characters will be featuring a problem that they're struggling with.

It's your job to find the mistake and help them solve it correctly.

Let's see who needs our help today?

It looks like Value Pack needs our help.

Value Pack is decomposing teen numbers, but seems to be having a problem.

Do you think you can help Value Pack?

Do you see some of his errors?

Let's see what the girls are thinking.

Sunshine says, "When I build 17 on my place value strips, it decomposes into 10 and seven, not six and 10."

Hm.

Are you thinking what Sunshine was thinking?

I think we need to take a closer look at it on mine.

Okay, so the first thing we're going to do is put the number bond of 17 and six and 10.

Now, Sunshine said, when she looked at the number 17 on her place value strips, when she decomposed it, which means she's going to take it apart because remember, Value Pack can click apart and show each individual value.

So we're going to do that.

She said, "The two parts are 10 and seven, and that's not the same as six and 10."

So let's build it on our double 10 frame mat to triple check our work.

We're going to put 17 on our double 10 frame mat, which will look like this.

We have five, six, seven, eight, nine, 10.

And then 11, 12, 13, 14, 15, 16, and 17.

Now the two parts are 10 and seven.

You can see 10 on top and seven on the bottom.

So, I think Sunshine is correct.

I think we need to race that six and put a seven inside of our number bond.

This was great, and I know that Value Pack would be so proud of your help, but they're still more number bonds that they need help with.

Let's take a look at what Mariah is thinking.

Mariah says, "I know when I put together 10 and four, it is 14, not 15.

I think Value Pack meant to do 10 plus five equals 15."

This is another great observation.

We can go ahead and do the same thing that we did with Sunshine with Mariah.

Let's do that now.

So here we have it on our double 10 frame mat, the number 15 with 10 on top and five on the bottom.

Then we have our number bond with 10 and four.

Now, Mariah said, "When I see the number 14, I take it apart and see 10 and four."

Hm.

I think this is where the mistake is.

She said it should be 10 and five.

And I agree with her.

If you look at the 10 frame mat, we have 10 on top, and one, two, three, four, five on the bottom.

So our two parts should be 10 and five.

So let's go ahead and fix that in our number bond.

We'll erase the four and put the five.

Now I think Value Pack would be so impressed with our work, but we have one more number bond to help him with to set him straight.

Let's work on that one together.

So let's take a look at this last number bond.

It's 13 and it's decomposed into three and nine.

I have it all laid out for us on my whiteboard.

Let's take a look at it and solve it together.

You can see that I have the double 10 frame mat and the number bond.

So when we look at the two parts, we have three and nine.

I have nine on top and three on the bottom.

Let's count them.

We have nine, 10, 11, 12.

Hm, that doesn't make sense.

We need the number 13.

I thinking we need to take one more counter and put it in the top 10 frame to make a 10.

Then let's see if we get the number 13.

So I'll add that one up there.

Now we have 10, 11, 12, 13.

And if I grab my place value strips, you can see that 10 and three make our number 13.

So the last thing we need to do is change our number bond and put a 10 in there.

Wow, this was a great discovery in helping Value Pack.

You know that you're becoming a mathematician when you can find errors in math and solve them correctly.

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

It says, I can add and subtract within 20.

Let's take a look at this.

What do you notice?

What do you wonder?

I'm noticing that the kids are playing a game with marbles.

I've never played a game like this before.

I'm curious to find out more about it.

Let's see what the girls are thinking.

Sunshine says, "I see three kids playing a game.

They're playing with marbles."

And Mariah says, "There is a triangle on the ground."

Those are some great notices.

Let's talk about them a little bit more.

There are one, two, three kids that are playing a game and you can see the marbles scattered all over.

And Mariah said she saw a triangle on the ground.

These are really great notices.

Let's take a look at their wonders.

Sunshine is wondering, "How many marbles are in the triangle?"

And Mariah is wondering, "How do you play the game?"

These are awesome wonders.

Let's take a look at Sunshine's wonder first.

She was wondering, how many marbles are inside of this triangle.

So I think the easiest thing for us to do would be just to count them altogether.

Let's do that now.

One, two, three, four five, six, seven, eight, nine, 10, 11.

There are 11 marbles inside the triangle.

Now Mariah wants to know, how do you play this game?

I was wondering the same thing too.

So I have a slide that is going to tell us all about how to play the game.

The game is called playing Cincos.

These kids are playing a game called Cincos, which has played in Guatemala.

In the game, you try to knock other people's marbles out of the triangle that's drawn on the ground.

I think we could practice addition and subtraction to 20 with different scenarios of playing Cinco.

Let's give it a try.

The first problem says, there were 15 marbles inside the triangle.

Tyler knocked some of the marbles outside of the triangle.

There are seven left.

How many marbles did Tyler knock outside of the triangle?

This sounds like an interesting problem.

Let's work it out together.

So let's add 15 counters to our double 10 frame mat.

One, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, and 15.

The next part says, Tyler knocked some out, but he didn't tell us how many.

That's what we're trying to figure out.

The next part of our sentence says, there are seven left.

So, let's flip seven of our counters over to show the ones that are left.

We can go like this, one, two, three, four, five, 6, 7.

Those are the seven that are left.

Now I have some that are red.

Those are the ones that were knocked out of the triangle.

Let's count them together.

And some of you are probably really good at subitizing, so you're probably looking at this and you already know the answer.

Let's count them anyways.

One, two, three, four, five, six, seven, eight.

There were eight marbles that were knocked out of the triangle.

We started with 15 marbles in the triangle, then some were knocked out.

That's this part right here.

Then there were seven that were left inside the triangle.

Our, hm, the red part, was eight.

There were eight that were knocked out of the triangle.

This is a great way for us to show part, part and total.

I wonder if there's another way we could solve this problem.

I think I have a math might friend that would be able to help us with it.

It's my friend, Springling.

Springling is a Math Might that lives in Mathville.

Springling is very fancy.

She has fluffy eyelashes, long fur, and a tail that's shaped like a spring.

Springling likes to hop on the number line in friendly chunks.

Then when she is done, she likes to count how far she's gone to solve.

Let's see if we can solve a problem with our friend Springling.

All right, so our problem says 15 minus seven equals, hm.

We're going to try this a different way.

I have a double 10 frame laid out for us and an open number line.

Let's take a look and solve this together.

All right, so we're thinking back to those seven marbles that were left inside of our triangle.

I've got that on our double 10 frame mat here, and I'm going to start right down here on my seven.

Then I want to move forward on my number line with Springling.

You're probably wondering, where are we going to move to?

Well, let's look at our double 10 frame mat for some help.

We have seven in here.

Let's see what happens when we go eight, nine, 10.

We can go to the next friendly number.

So we're going to go on seven and jump to that 10.

And we know we needed three more to get to 10.

Now we're trying to go all the way to 15, because that's the number of marbles that we started with.

So I'm going to add some more counters to my double 10 frame.

We need to add 11, 12, 13, 14, 15.

So now on my number line, I'm going to go from the 10 to that 15.

And you know, just by subitizing, that's five.

Now I can add these two numbers together, which gives me the total of eight.

And you can see that on the double 10 frame.

We'll go up to our problem that says, 15 minus seven equals eight.

Wow, Springling would be so proud of your work.

You did a great job of using the open number line to go from seven to 15.

Now, let's try another problem.

This problem says, Jane won six marbles, then one another 12 marbles.

How many marbles did she win in all?

Let's go over to the double 10 frame mat and solve this together.

We'll start with the six marbles that Jane won first.

One, two, three, four, five, six.

Then it said, she won 12 more marbles.

So I want you to think, am I adding or am I taking away?

You're right, we're adding this time.

So let's add 12 more counters to our double 10 frame mat.

One, two, three, four, five, six, seven, eight, nine, 10, 11, 12.

Now, before we go any further, let's start to write this expression out.

We started with six and we added 12, and we wanted to know how many marbles does she have in all.

I think we should take a look at it and add them up together.

Because the top 10 frame is full and then say 11, 12, 13, 14, 15, 16, 17, and 18.

So, six plus 12 equals the total of 18.

Now it's your turn to play Add 7, 8, or 9 Bingo to practice some of the strategies we used today.

Great work today, first grade Math Mights.

We were able to do a mystery math mistake and add and subtract to 20.

Until I see you next time, I want you to kiss your brain.

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- [Child] Changing the way you think about math.

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