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This is the video for
the measuring angles

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module because, clearly, at the
time that I'm doing this video,

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there is no video for the
measuring angles module.

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And this is a
pretty neat module.

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This was made by Omar Rizwan,
one of our amazing high school

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interns that we had
this past summer.

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This is the summer of 2011.

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And what it really is, is
it makes you measure angles.

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And he made this really
cool protractor tool here

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so that you actually
use this protractor

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to measure the angles there.

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And so the trick here is you
would actually measure it

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the way you would
measure any angle using

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an actual physical protractor.

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You'd want to put the center
of the protractor right

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at the vertex of where
the two lines intersect.

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You can view it as the
vertex of the angle.

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And then you'd want
to rotate it so

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that, preferably, this edge,
this edge at 0 degrees,

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is at one of these sides.

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So let's do it so that
this edge right over here

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is right along this line.

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So let me rotate it.

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So then-- I've got to rotate
it a little bit further, maybe

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one more.

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No, that's too far.

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So that looks about right.

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And then if you
look at it this way,

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you can see that the angle-- and
I don't have my Pen tool here.

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I'm just using my
regular web browser--

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if you look at the
angle here, you

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see that the other line
goes to 130 degrees.

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So this angle that we
need to measure here

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is 130 degrees, assuming
you can read sideways.

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So that is 130 degrees.

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Let me check my answer.

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Very good, I got it right.

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It would have been
embarrassing if I didn't.

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Let's do the next question.

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I'll do a couple of
examples like this.

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So once again, let us put the
center of the protractor right

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at the vertex right over there.

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And let's get this
0 degrees side

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to be on one of these sides
so that this angle will

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be within the protractor.

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So let me rotate it this way.

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And this really is pretty cool
what Omar did with this module.

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So let's see.

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Let's do it one more time.

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That's too far.

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And so that looks about right.

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And then you can see that
the angle right over here,

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if we look at where the
other line points to,

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it is 40 degrees.

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Check answer-- very good.

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Let's do another one.

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This is fun.

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So let's get our protractor
right over there.

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And you don't always have
to do it in that same order.

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You could rotate it first
so that the 0 degrees is--

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and what you want to do is
you want to rotate the 0

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degrees to one of the sides
so that the angle is still

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within the protractor.

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So let's rotate it around.

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So if you did it like
that-- so you don't always

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have to do it in
that same order.

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Although I think it's
easier to rotate it

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when you have the
center of the protractor

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at the vertex of the angle.

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So we have to rotate
it a little bit more.

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So 0 degrees is this line.

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And then as we go
further and further up,

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I guess, since this
is on its side,

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it looks like this other
line gets us to 150 degrees.

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And hopefully you're noticing
that the higher the degrees,

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the more open this angle is.

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And so this one right
over here is 150 degrees.

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And so let's do that-- 150.

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Let's do one more.

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Now let me show
you what not to do.

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So what not to do
is-- so you could

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put the center right over there.

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And you might say,
OK, let me make

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the 0 go right over on
this side, right over here.

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So if you did that, notice
your angle would not

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be within the protractor.

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So you won't be
able to measure it.

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And what you're attempting to
do is measure this outer angle

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over here, which is
an angle, but that's

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not the angle that this question
is asking us to measure.

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This little arc over
here is telling us

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that that's the angle
that we need to measure.

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So that arc has to be
within the protractor.

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So let's rotate this
protractor a little bit more.

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I overdid it.

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And so this looks like
this is 0 degrees,

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and then this right
over here is 60 degrees.

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60 degrees-- we got
that one right, too.

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So hopefully that helps
you with this module.

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It's kind of fun.