(upbeat music) - [pupils] Math Mights.

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

I have a ton of math activities planned for us.

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

Today we'll be doing a mystery math mistake and expressions that can be equal.

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!

D.C. is holding Abacus's wand, what is going on?

Here is how our mystery math mistake is going to work.

One of our Math Might characters will feature a problem that they're struggling with.

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

Let's see who needs our help today?

It looks like D.C. needs our help.

I think he is struggling with number bonds.

Let's see if we can help him to decompose the number bonds correctly.

Do you see the errors that are in the number bonds?

Let's see what Jameson thinks.

Jameson says, "I know that seven and two make nine, not 10.

I think it should be seven and three."

I have a 10 frame laid out in front of me and we're going to draw that number bond right here, where D.C. decomposed it as 10 and seven and two.

Now Jameson said, well, let's build it first.

Let's put in seven.

One, two, three, four, five, six, seven, and then one and two.

So looking at it, you can automatically see that something's not right, because we're trying to get to the number 10.

And Jameson said, 10 is seven and three, not seven and two.

So let's put one more counter on there and see if Jameson is correct.

We'll put in that third counter and now our 10 frame mat is full, so we know that seven and three make 10.

So I'm going to go ahead and change that number in D.C.'s number bond.

D.C. would be so proud of our help today, but I think there are still more number bonds that have some errors.

Let's see what Josiah thinks.

Josiah said, "I know that six and five is over 10.

I think D.C. meant for it to be six and four, which equals 10."

Ooh, this is interesting.

Let's take a look at mine and build it together and see if we can find the mistake.

Let's build it on my 10 frame.

We'll start with six, and then we'll put on five.

Hmm, I think Josiah is right.

He said six and five is over 10, and when you look at it, I have one counter that won't fit inside of my 10 frame.

So I'm thinking we need to try taking away that one counter to see if that makes 10, like Josiah said.

So if I take this one off, I have six and four, which makes 10, Josiah was right.

Let's go ahead and change this into six and four.

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

It says, "I can think about how expressions can be equal."

Let's take a look at this slide.

What do you wonder?

What do you notice?

Well, I notice that this looks like a seesaw or a teeter-totter that you might see at the park.

Let's see what the boys are noticing.

Jameson says, "I see a seesaw with blocks on it."

And Josiah says, "One side of the seesaw has more cubes on it."

Well, I happen to have it blown up here in front of me, so let's take a closer look at it.

Here's what you can see.

I can see that Jameson said, I see a seesaw, which is this right here.

It looks something similar to what you would see at a park or a playground.

And he said that there are some blocks on it.

And there are some blocks on each side, and they're kind of crooked.

And, Josiah says, one side of the seesaw has more cubes on it.

When you're looking at this, I can tell that this side has more cubes on it than this side.

And I can kind of tell that those cubes are kind of weighing that side down, it's a little bit heavier.

Now, these are great mathematical notices.

Let's take a look at their wonders.

Jameson says, "Can we write an expression for the red and yellow blocks?"

And Josiah says, "How can we make the two sides the same or equal?"

These are great wonders and I think we can solve them together.

Let's try it.

The first one is where Jameson says, "Can we write an expression for the red and yellow blocks?"

Sure, I think we could start with the yellow block and put a one.

Plus the red blocks which would be one, two, three.

Then we could count them all up and see that we have one, two, three, four blocks in all.

And, I think we could even write an expression for the side that just has the red blocks.

Let's give it a try.

What do you see on the other side?

You see one, two, three red blocks plus, how many yellow blocks do you see?

You don't see any.

So we're going to write the number zero.

And we know that three plus zero equals three.

Now, Josiah wants to know, how can we make both sides the same or equal?

Well, in order to do that, we need both sides to have the same amount on it.

So when we look at this, we can see that this side is way down more because this side has a total of four, but this side only has a total of three.

So are you thinking what I'm thinking?

I think we need to add one more block because the seesaw is tilted this way and we need to level it out so that it's balanced or equal.

So when I look at this, I see I have one and one that match up, these match up and these two red match up, but I missing a yellow on this side.

So I'm going to grab my yellow marker and make a yellow block up at the top.

Now, if I had a real seesaw in front of me, now this would start to come down and it would be all balanced out.

Let's continue to work on making expressions equal.

Let's play a game called true or false.

Here's how it's going to work.

I'm going to show you two expressions and we need to decide if they are equal or the same.

I need you to pay attention to the equal sign in the middle because that's going to help us to decide if this is true or false.

If it's true, I want you to give me a thumbs up.

If it's false, I want you to give me a thumbs down.

Let's take a look at our first one.

It says, two plus four equals four plus two.

So, I want you to look at that equal, does what's on the left equal the exact same thing that's on the right?

I have it in front of me and we can work it out together.

Today I brought with me the two cards that show two plus four and four plus two.

I also brought a balancing scale.

We want it to balance in the middle.

We don't want one side to be farther down than the other.

If it's like that, then it won't be equal.

We'll start by building two plus four.

So I'm going to put in one, two cubes that are yellow, and then I'm going to put in four, one, two, three and four.

Now on the other side, I'm going to start with four yellow.

And let's see if anything happens to our scale as we're doing it.

One, two, three, four, and one, two.

You can see that our scale is now equal.

Both sides are balanced out because two plus four is the same or equal to four plus two.

So that would be a thumbs up.

Let's try another combination.

You need to make sure that you pay attention to the equal sign.

You wanna make sure what's on the left is equal to what's on the right.

Both sides have to be the same, otherwise it's going to be a thumbs down false.

It says, three plus six equals six plus four.

Do you think that this is a true or a false?

Let's take a closer look at it.

Again, I have both expressions in front of me, three plus six and six plus four.

I'm going to try to balance my scale out to prove if this is true or false.

So we're going to start with the yellow and put in one, two, three.

Then I'm going to add six red, one, two, three, four, five and six.

Next on this side, I'm going to put in six yellow, one, two, three, four, five and six, and then four red, one, two, three, oh oh, my scale is really starting to move, and four.

Uh, when I look at this now, the right side is farther down than my left side, which is telling me they're not equal.

That must mean that the right side has more than the left side.

Now I could put the cubes together and we could take a closer look to see what the difference is.

So if I put my red cubes back together, I could show you, here is three and six.

Then if I put the cubes together on this side, I have my six yellow cubes and four red cubes.

You can see by comparing them, hmm, I have more on the bottom one than I do on the top.

You can see each of them have a partner all the way up to this end.

So I would either need to take one red off to make it equal, or, I would need to come over here maybe and grab another yellow to make it equal.

So if you said thumbs down, you were right.

That was fun.

You're getting really good at deciding if expressions are equal or balanced.

Now let's play a game called equal sum duel.

Here's how it's going to work.

You can see on the screen that I have two different stems or sentences, and then I have two different sets of expressions.

The first expressions are eight plus two, six plus four.

The stem says, the sum of eight plus two is equal to the sum of six plus four because, and they're equal because eight plus two equals 10 and six plus four equals 10.

So we can use that stem for those expressions.

On the other side, the two expressions are three plus two and four plus three.

The stem says the sum of three plus two is not equal to the sum of four plus three, because we know that three plus two is five and four plus three is seven, and those two numbers are not equal, they are not the same.

So that's why we chose that stem.

Let's see what Jameson is thinking.

Jameson is thinking about two expressions, six plus three and four plus four.

Let's explain his thinking.

I have it in front of me here, six plus three and four plus four.

I know that you're getting really great at adding and I know that you know that six plus three equals nine.

So I'm gonna write that here just so I can remember it.

Then, four plus four equals eight.

Hmm, I'm looking at these and they're not the same.

Nine is not the same as eight.

So that means I'm going to have to use the stem that says not equal.

So right here I would say, the sum of six plus three is not equal to the sum of four plus four, because nine is not the same as eight.

So this time I don't get to keep the card, but if the two expressions were equal, I would get to keep the card and then I would continue playing until all the cards were gone.

Now it's your turn to play equal sum duel.

Remember, you can play until all the cards are used up and the person with the most cards wins the game.

First grade Math Mights, I had a blast with you today.

We were able to solve a mystery math mistake, helping D.C. decompose the number 10.

And then we were able to make expressions equal.

Until I see you next time, kiss your brain.

(bright music) (upbeat music) - [Narrator] sis4teachers.org.

Changing the way you think about math.

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