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## Fractions intro

Current time:0:00Total duration:3:48

# Recognize fractions

CCSS Math: 3.NF.A.1

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## 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.