Add Subtract Fractions PPT.pdf

meaning members.

I am the seventh grade math teacher.

Mr Serrata.

I am also the department chair for still middle school.

Today, I'm going to be talking to you about adding

end subtracting fractions with unlike denominators, so adding and subtracting

fractions with unlike denominators does require that we first review

our skills in equivalent fractions.

So equivalent fractions are fractions that have the same value.

Uh For example the fraction one half to 4th and

36 all have the same value, they're just presented differently.

So down here at the bottom you see that I

have a pizza on the left that has been cut

into halves of the upper half and the lower half

in order to model or describe visually what The equivalent

of one half if it is in terms of 1/4

or fourth is if you notice this pizza here Was

cut into 2/4.

Therefore I know that every half a pizza is equivalent

to 1/4 which is what we did up here.

Yeah students, let's see if you can Copy This pizza

or start fresh with a new one.

See if you can model the half into the 36

How does 36 equal to one half?

That will be our first challenge on this video or

for this lesson.

The second part that we're going to do is we're

gonna ask ourselves, how do you make an equivalent fraction?

Well to make an equivalent fraction And we're going to

take the example that we have here on our screen

one third and 26 I want to make those equivalent

fractions. So what I need to do is multiply or

divide A fraction by another fraction.

That is equivalent to one in elementary.

Some teachers call it the special one In other words

multiply or divide the numerator and denominator by the same

number. So here I have the fraction 1/3.

I'm gonna multiply one times 2 and the three which

is my denominator.

I'm gonna multiply it times two so that I can

get that common denominator of six at the bottom.

And that's what we see here on this example.

One half plus 1/4.

Does not have does not equal.

I'm sorry 2 to 6.

Why? When you're adding fractions you do not add just

across. Okay.

Unless those fractions have an equivalent or same denominator.

Okay so the two and the four would have to

be the same number in order for us to be

able to do that.

Um So the steps are adding and subtracting fractions will

be first, we're going to find a common denominator just

like we see here in step number one.

Now to find a common denominator, you can either multiply

the denominator or find the least common multiple by listing

all the multiple multiples of both.

So on the left side, excuse me.

On the right side you have the red writing.

That's what we're going to be looking at.

I have the fraction one half, Add it to the

fraction 1/4.

I can multiply the two and the four to get

eight, which is a common denominator.

Or I can list the multiples of two and four

until I find the least common multiple that two and

four half The least common multiple between two and 4.

We see it here and it is four.

But Mr Kurata earlier you said I could use 8.8

is a common multiple of two and four, but it's

not the least common multiple.

In other words, you could still use the eight.

You're just not going to get the fraction.

In simplest forms, you're going to have to simplify at

the end.

Okay, so step number two, I'm gonna want to convert

1/4 and excuse me, one half and 1/4 into its

equivalent fraction with a common denominator.

And in this case we multiplied uh and we got

4/8 and 2/8.

Okay, I wrote those fractions into an equivalent fraction.

Step number three, we're gonna write the excuse me, Step

number three, we're going to write the equivalent fractions.

That one half is 4/8.

I put it right under its equivalent that 1/4 is

equal to 28 And I put it right under the

equivalent notice an equivalent fraction, notice that I have a

denominator of eight on my first fraction and a denominator

of eight on my second fraction.

Now I can add my enumerators four plus two is

six. And remember we do not add the denominator, so

I just carry the eight over.

So my answer here is six out of eight when

I add these two fractions Now on step number four

I always want to make sure that I can simplify

my fractions or check to see if they can be

simplified in order to do that.

I want to find or try to find a greatest

common factor between six and eight.

And the reason you want the greatest common factor is

because it will ensure that you get the fraction in

simplest forms every now and then you may have to

simplify a second time just because of the way the

numbers work.

But generally speaking um this pretty much does the trick.

The greatest common factor between six and 8 Is too.

So that means that I divided 6.2.

Okay and that's gonna give me three and I'm going

to divide the eight by two and that's going to

give me four.

Excuse me.

So that's gonna be my my answer here.

When I simplify the answer 68 it's gonna give me

3/4 ladies and gentlemen, I thank you very much for

listening. I want to just remind you that this is

a creation that I borrowed.

Um you may find the full presentation at this link

right here again.

My name is Mr Serrata.

My email is listed below.

Are proud principle is Mr Albert Leon and I do

have is email address there.

If you have anything that you would like for me

to present on.

You're more than welcome to email me directly or you're

also welcome to email Mr Leon.

I want to thank you very much for listening and

have a great day.

Add Subtract Fractions PPT.pdf

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