(soft music) - [Children] Math mights!

- Hey math mights, welcome back!

And if it's your first time joining us, 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'll be solving a mystery math mistake.

And then, we'll be solving more story problems.

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, and I need your help to try to figure out the mystery math mistake.

Okay, here's how it works.

I'm going to act out a problem with a concept that you're familiar with, and you're going to try to figure out my mystery math mistake by using your magnifying glass.

Not a real magnifying glass, you can use one just like this with your hand and be a math detective.

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

Let's check out our first problem.

Oh, I see D.C.

He is upside down and all turned around.

I think he got his strategy mixed up.

Our math problem says 25 plus 28.

Let's solve it together.

I have D.C. here with me.

And remember, D.C. likes friendly numbers.

He likes numbers that he can decompose into tens.

He wears a hard hat and has a mallet, and he can smash the numbers that aren't friendly numbers and make them into friendly numbers.

Let's try it here.

I have 25 plus 28.

I'm going to decompose that 25 into 23 and two.

Then I can take the two and the 28, and it's going to make 40.

I'm going to take the 23 plus 40 and it equals 63.

Did you get the same answer I did?

Or, are you able to find my mystery math mistake?

Well let's see what our friends Rocco and Aidan think.

Rocco says, "It looks like D.C. decomposed "the 25 into 23 and two correctly."

Aiden says, "I think he made a friendly number, "but he didn't solve the problem correctly.

"28 plus two doesn't equal 40, it equals 30.

"23 plus 30 equals 53."

Did you figure out the mystery math mistake?

I bet you did.

Let's go and fix it together.

So, you can see right here where I made my mistake.

I have 23 plus, and 28 plus two is not 40.

28 plus two is 30.

So I know that 23 plus 30 equals 53.

Great work Aidan catching that math mistake.

And great job first grade math mights if you found that mistake too.

Finding math mistakes in math problems makes us all better mathematicians.

It really helps us to slow down and look at the problem, and make sure we're doing all the steps we need to do to add or subtract correctly.

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

It says, "I can solve story problems "with unknowns in all positions."

I think I have a math might here to help me today.

Let's see who's here to help.

Professor Barble.

And do you remember Professor Barble?

He loves word problems.

And if he slows down to think about what the problem is really asking, and he presses on his cap, all of these really cool tools will come out to help him create a picture of what the problem is asking him.

You might be wondering, what is a visual model?

A visual model is sometimes known as a model drawing, unit bar, tape diagram or bar model.

Drawing a visual model helps us visualize the strategies and understand what the word problem is asking.

A visual model is also a reading comprehension strategy for word problems.

Professor Barble wants us to use his seven step visual model process to solve our word problem.

Let's do it together.

Step number one is for us to read the entire problem and put in the chunks.

I'll read it one time for you, and then together we'll go back and put in the chunks.

The problem says, "Elena bought a bag "of beads to make a bracelet.

"She takes out nine beads to make a bracelet.

"There are 11 beads left in the bag.

"How many beads were in the bag when Elena bought it?"

All right, we've read it one time through.

Now let's go back and chunk it for information.

You can read it along with me.

It says, "Elena bought a bag of beads to make a bracelet.

"She takes out nine beads to make a bracelet."

That's where we add our first chunk.

Then it says, "There are 11 beads left in the bag."

We add another chunk.

Then it says, "How many beads were in the bag when Elena bought it?"

Let's add our last chunk.

We have three parts of information.

Now, step two is when Professor Barble wants us to rewrite the question in sentence form with a blank space for the answer.

In first grade, we usually help you with this part.

So if you take a look at mine, you can see I have the sentence written for us.

It says, "There were hmm beads in the bag "when Elena bought it."

Step number three, we're going to add the who or what that is in the problem.

On mine, you can see the who or what is Elena's bag of beads.

Next, we make our visual model.

I've done that for you this time.

Our visual model bar is right here.

Our next step, step number five, is my favorite part.

It's when we get to add the information we chunked, and then we check it off as we go so that we make sure we don't miss any of our information.

It says, "Elena bought a bag of beads to make a bracelet.

"She takes out nine beads to make a bracelet."

So the first part that I'm going to add are the nine beads.

I'm going to draw a line.

I'm going to put a nine here.

And then I'm going to say, I'll label it with a T for takes out.

I'm going to go up, and check it off.

My next part says, "There are 11 beads left in the bag."

So that must be the part I'm going to add right here.

I'm going to put in an 11.

Put an L for left.

Go up, and check it off.

Then it says, "How many beads were "in the bag when Elena bought it?"

That part right here is my hmm.

That's the part I don't know.

And I want to go back up and check that off.

Now, I have all of my parts entered into my visual model.

My next part, step number six, is to correctly compute and solve the problem.

There's that big word compute.

We need to determine, do I need to add, or do I need to subtract?

I can see that since my question mark is at the end of my visual model, I need to add these two parts.

So I'm going to add nine plus 11 to get the total of beads that were in the bag when Elena bought it.

So down here, I'll do nine plus 11 equals hmm.

Now, if I was really thinking on how to solve this problem, I could probably use D.C. and decompose this 11 into a one and a 10.

And I could grab this and say 10 plus 10 equals 20.

So I know that she has 20 beads in her bag to start.

I have one last step.

I don't want you to get too excited that you solve the problem that you forget our last step.

Step number seven is to write the answer in the sentence and check.

Let's do that together.

We'll take our 20 and put it up here.

And now I know there were 20 beads in the bag when Elena bought it.

Awesome work math mights on solving that problem with Professor Barble.

You did a great job working through his steps.

Math mights, you've done such a great job with this, we're going to try another word problem, and we're going to change it just a little bit.

So let's read the problem.

It says, "Elena has some beads in a box.

"She uses five of them to make a bracelet.

"She has 10 beads left.

"How many beads were in Elena's box?"

My question to you is, which equation matches the story?

Five plus 10 equals hmm?

Hmm minus 10 equals five?

Or 10 minus hmm equals five?

Let's take a look at mine.

You can see that I've done all of Professor Barble's steps for us.

I've chunked my problem.

I've found my who or what.

I've added my information and checked it off.

And I've added my question mark.

I've written down those three different equations right here.

We need to decide which equation is the correct one.

So I think what's important for us to know here, is that if we didn't have this visual model, we might guess, do I need to add, or do I need to subtract?

But having the visual model will help me figure out which equation is the correct one to use.

So let's look at those equations a little bit closer.

I'm going to start here, where it says 10 minus hmm equals five.

Well, I know that I'm looking for the whole number, and since I have the two parts of 10 and five, five won't be what I'm looking for.

So I'm not subtracting 10 minus hmm to get five.

So this can't be correct.

I'm going to X it out, that's not right.

When I look at the middle one, hmm minus 10 equals five.

Again, I have my two parts and I'm looking for the whole, so I know I won't be subtracting again.

So this can't be right either.

I better X this one out as well.

Finally, this equation says five plus 10 equals hmm.

I think this one might be the one that I need.

I have the five and the 10.

Those are my two parts.

And I'm looking for the whole number.

And I know that five plus 10 equals 15.

So I need to finish my last step, which is to add the 15 to my sentence.

Elena has 15 beads in her box.

That was a lot of work, and it really took a lot of hard thinking.

But I think you did a great job math mights.

Since you are so good at this, I have one more question for you.

What is Professor Barble's word problem?

We've seen one like this before.

We have to work backwards to come up with our problem.

So you can see our information here.

We have Elena's beads.

She has some that are used, some that are left, and the whole number of 12.

So when I think about this problem, I think that since I have the whole number of 12, and she used three of them, and there are some left, I'm thinking this is going to be a subtraction problem.

Since I have the whole number 12 and I can take three away, I'll be able to figure out the hmm, or how many are left.

Let's do that now.

I'll write the 12, which was my whole number, or all of her beads, minus the three that she used equals this part that's left.

And just so that we can make sure we're doing it correctly, let's count how many are left.

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

So I'll write my nine down.

12 minus three equals nine.

Were you able to come up with that word problem like I was?

I bet you were.

Now it's your turn to solve more word problems with my friend Professor Barble.

First grade math mights, I had so much fun with you today.

We were able to solve a mystery math mistake, and we were able to do more story problems together.

And during that whole time, we were able to use all of Professor Barble's step-by-step visual model process.

Until I see you next time math mights, kiss your brains.

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