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### Course: Class 5 > Unit 4

Lesson 2: Recognise fractions# Recognize fractions

Sal uses fractions to name parts of a whole. Created by Sal Khan.

## Want to join the conversation?

- if you have fractions when in life would you need to use equivalent fractions ?(26 votes)
- If you wanted to divide something into equal parts...say you have six guests over and you are cutting it out and mom asks how much is left and there is 1/6 left.....without fractions you would be in a dilemma....does that help?(15 votes)

- If I had 7 pet fishes 3 of them are red and 4 are gold how would I write this in fraction form and include all the given information (7 pets,3 red and 4 gold)(7 votes)
- One way to put this information in fraction form is 3/7 and 4/7 since 7 is the denominator which is the total number and the three and four are parts of 7.(6 votes)

- if you cut a pie and split it into 10 equal group then your brother comes and eat 5 slices will it be 10/5(7 votes)
- can any number be a fractions?(4 votes)
- Yes. For example,
`0.78`

can be expressed as`78/100 = 39/50`

.`23`

can be expressed as`23/1`

or as`46/2`

if not simplified.(7 votes)

- If the fraction is like 1/9 is it unit or proper fraction?(2 votes)
- 1/9 is a proper fraction.

A proper fraction is any fraction where the numerator is less than the denominator. (like 1/9).

An improper fraction is any fraction where the numerator is greater than the denominator. (like 10/9).

A unit only refers to a fraction where the numerator and denominator are equal. (like 9/9).(8 votes)

- Why didn’t they solve the last problem(3 votes)
- He did h was explaining that it wasn't even(5 votes)

- if equivilent fractions are multiplying,what is dividing fractions called?(5 votes)
- Sal says a ninth tounge twister(4 votes)
- I think Sal means is that it is tounge twister number nine but basically a tounge twister is something that you have to twist your tounge.(1 vote)

- It does not help.(4 votes)
- Are you talking about tounge twisters? I guess so. Comment if you think I'm right(1 vote)

- why wont sal get to the point that we need help 💔?(4 votes)

## Video transcript

I have a square here divided
into one, two, three, four, five, six, seven, eight,
nine equal sections. And we've already seen that
if we were to shade in one of these sections, if we were
to select one of these sections, let's say the middle
one right over here, this is one out of the
nine equal sections. So if someone said, what
fraction of the whole does this purple
square represent? Well, you would say, well, that
represents 1/9 of the whole. This thing right over
here represents 1/9. Now what would happen if we
shaded in more than that? So let's say we shaded in this
one and this one, let me shade it in a little bit better. And this one and this
one right over here. Now what fraction of the
whole have we shaded in? Well, each of these, we've
already seen, each of these represent 1/9. So that's 1/9, that's 1/9. When I say 1/9, I
could also say a ninth. So this is 1/9 or a
ninth, so each of these represents a ninth. But how many of these
ninths do we have shaded in? Well we have one, two,
three, four shaded in. So now we have a total
of 4/9 shaded it. 4 of the 9 equal
sections are shaded in. So 4/9 of the
whole is shaded in. Now let's make things a
little bit more interesting. Let's shade in. So here I have five
equal sections. Let me write this down. I have five equal sections. And let me shade
in five of them. So one, two, three, four, five. We already know that each
of these sections, each of these situated in
sections represent 1/5. So 1/5, another way of saying
that is a fifth, is 1/5. But now how much do
I have shaded in? Well I have five out of the
five equal sections shaded, or I have 5/5 shaded in. And you might be
saying, wait, wait, if I gave five out of the
five equal sections shaded in, if I have 5/5 shaded in, I've
got the whole thing shaded in. And you would be
absolutely right. 5/5 is equal to the whole. Now what I want you to
do is pause this video and write down on
a piece of paper or at least think
in your head, what fraction of each of these
wholes is shaded in? So let's go to this first one. We have one, two, three, four,
five, six equal sections. And we see that one, two,
three, four are shaded in. So 4/6 of this
figure is shaded in. Let's go over here. We have one, two, three,
four, five equal sections. And one, two, three,
four are shaded in. So here, 4/5 of this
circle is shaded in. Now in this figure, I have two
equal sections and both of them are shaded in. And this we would say two halves
of this figure are shaded in. And once again, if two
halves are shaded in, that means everything
is shaded in, that this represents a whole. Now this one right
over here it might be tempting to say, I
have one, two, three, four sections and
one, two, three have been shaded in so
maybe the red represents 3/4 of the figure. But remember, the sections
have to be equal sections. And this red section
is way bigger. It actually looks like it's
bigger than the other three combined. So you do not have four
equal sections here. So at least based
on how it's drawn, you can't say that 3/4
is actually filled in.