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This is the video for[br]the measuring angles

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

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there is no video for the[br]measuring angles module.

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And this is a[br]pretty neat module.

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

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interns that we had[br]this past summer.

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This is the summer of 2011.

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And what it really is, is[br]it makes you measure angles.

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And he made this really[br]cool protractor tool here

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so that you actually[br]use this protractor

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to measure the angles there.

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And so the trick here is you[br]would actually measure it

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the way you would[br]measure any angle using

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an actual physical protractor.

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You'd want to put the center[br]of the protractor right

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at the vertex of where[br]the two lines intersect.

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You can view it as the[br]vertex of the angle.

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And then you'd want[br]to rotate it so

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that, preferably, this edge,[br]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[br]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[br]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[br]look at it this way,

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

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I'm just using my[br]regular web browser--

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if you look at the[br]angle here, you

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see that the other line[br]goes to 130 degrees.

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So this angle that we[br]need to measure here

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is 130 degrees, assuming[br]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[br]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[br]examples like this.

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

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at the vertex right over there.

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And let's get this[br]0 degrees side

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to be on one of these sides[br]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[br]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[br]the angle right over here,

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if we look at where the[br]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[br]right over there.

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

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

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and what you want to do is[br]you want to rotate the 0

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degrees to one of the sides[br]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[br]that-- so you don't always

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have to do it in[br]that same order.

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Although I think it's[br]easier to rotate it

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when you have the[br]center of the protractor

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at the vertex of the angle.

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So we have to rotate[br]it a little bit more.

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So 0 degrees is this line.

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And then as we go[br]further and further up,

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I guess, since this[br]is on its side,

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

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And hopefully you're noticing[br]that the higher the degrees,

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the more open this angle is.

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And so this one right[br]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[br]you what not to do.

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So what not to do[br]is-- so you could

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put the center right over there.

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And you might say,[br]OK, let me make

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the 0 go right over on[br]this side, right over here.

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So if you did that, notice[br]your angle would not

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be within the protractor.

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So you won't be[br]able to measure it.

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

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over here, which is[br]an angle, but that's

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

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This little arc over[br]here is telling us

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that that's the angle[br]that we need to measure.

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So that arc has to be[br]within the protractor.

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

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I overdid it.

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And so this looks like[br]this is 0 degrees,

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and then this right[br]over here is 60 degrees.

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60 degrees-- we got[br]that one right, too.

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So hopefully that helps[br]you with this module.

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It's kind of fun.