>> Susan Osterhaus: Okay.
Well, we have been
using the compass
to draw concentric
circles, we've used it
to construct a Venn
diagram, we've used it
to construct the perpendicular
bisector of a line segment,
and something that a lot
of students need to do
but usually have difficulty
doing is creating a
circle graph.
So I'm going to go
ahead and -- and see --
see if I can make you
a nice circle graph,
but this time using
the Draftsman,
with its special film.
And I'm going to use a Fiskars
compass, with the stylus
that actually comes with
the -- with the Draftsman.
So we're going to -- and --
and remember I worry about
stabbing the Draftsman
with the Howe Press
compass, and I'm still going
to do a little bit of stabbing
this time around, but I'm going
to use the Fiskars, but I'll --
I'll explain what I'm trying.
Okay, so it's -- it's a
little gentler, and I'm going
to go ahead and try to
draw my -- my circle first.
And hopefully it's not
going to be too light.
[ Silence ]
Alright. I'm going to go over
it one more time, just --
and the student --
believe me, the student --
your student will be
checking all of this out.
Actually they'll be
going oh do I like that?
And -- and that's what you
should caution them to do
that before they lift it up,
especially with the Fiskars,
'cause it's -- it's
stabbing, but it doesn't --
it's just a rubber
tip, so it doesn't have
as good a stabbing technique.
What you're going to probably
want to do right then is somehow
if you can -- and this is
the part I worry about,
but try to actually get in
there with a ball point pen --
have your student get in there
so they actually can
stab a little bit
so that they can feel
where the center was.
Because your -- your
Fiskars is not going
to probably leave
a very good stab.
Okay. So I'm feeling that
little bump that's the center.
And keeping that in mind
then, I'm going to --
I'm going to go ahead
and put my pen there,
put my -- a -- a ruler here.
Because remember I'm making
a circle graph, and the --
all I needed was, you know,
to begin with was the
circle, which I created.
And now I'm going to draw a --
a circle graph, and the
first thing I'm going
to do is divide it in half.
So I'm going to pretend my
circle graph -- part of --
of the job was just to have a
circle graph that was divided
into half -- into 50% and 50%,
maybe that's a better
way to say it.
They'd need to come to the --
make sure they are feeling the
edge of the circle -- might --
might want to do
a little stab --
come there through the
center -- they'll feel it --
until they hit the other
side of the circle and stop.
And now what they've done --
actually I used a -- I used --
I keep using a pen, when I
really wanted to switch over
and just use the -- the stylus.
So let me go back over that.
It's going to be the same
feel, but sometimes the --
the stylus actually
makes the film work --
the film that's on the
Draftsman work a little better.
Okay. So this could
be a circle --
circle graph where you say 50%
of something is duh duh duh,
and 50% is such and such.
That was pretty easy, but most
circle graphs are not quite
that easy.
So the next thing you
might have to do is try
to get a circle graph, and
get a piece of that pie --
pie graph some people call
it -- that's like one-fourth.
Well, you have to think in terms
of what is one-fourth in terms
of a circle and degrees.
So this is where you get to
do a little more geometry.
So you grab your APH Braille
Print Protractor, and you know
that half of a circle, okay,
is like this protractor
-- 180 degrees.
And half of that,
which would be --
would be a fourth of the
whole circle, is 90 degrees.
So you're going to come up
here, find the 90-degree mark,
tighten it, and now what you
have created here is a 90-degree
angle on each side.
Now here's where you
have to be careful,
why I kind of stabbed there.
You've got to find the center
of the circle, and I'm going
to -- this is my technique.
I'm going to hold that like
that, bring my protractor
into it so that that's going
to be my vertex, because that's
where I need to draw my angle.
And I'm going to
draw straight down --
oops, I did what I always
tell students not to do,
put my thumb in the way.
I move my thumb.
And you don't really have
to draw the other part
of the angle, because
remember, it's already drawn.
So now you have a circle graph
that's 50% is bladie bladie
blah, 25% something
else, 25% something else.
Okay, that's how
you make fourths.
Okay, but, you know, we don't
always just have that either.
Again, got to do a little
geometry, little math.
Let's say that you wanted --
right about here you
wanted about a third.
Well you could kind of guess it,
but let's be exact,
we're in math class.
Okay, let's go back
to that 180, and --
but again it's got to really
be -- it's got to really be,
you know, a part of this circle.
Let -- let's -- let's
figure out what --
what we could have there.
If we wanted -- 'cause what we
want right now is just really a
-- a third of this.
How could we do that?
Well let's -- let's
try something here.
What if we did 60?
Because remember, we said
this whole thing is 180,
and if we just want
a third of this area,
which would actually be a
sixth of the whole circle,
well, think about that.
180 divided by 3 is 60, okay.
So which angle though?
Is it this angle or that angle?
Well, it's an acute angle,
so it's got to be this side.
Again, find that center, because
remember we stabbed it, it's --
we know where it is,
and slide that in there.
It's got to be right
at the vertex.
They've also got to be making
sure that right up against
that protractor is that
line they've already drawn.
So now that we're getting
more and more lines in there,
we've got to be a little
-- little more careful.
So we're going to need to make
sure that they've got that right
up against -- they
can even probably --
yes, you can even feel it
with the -- with the --
the edge of the protractor
there.
So you don't have
to draw this part
of the angle, it's
already drawn.
And then just draw this
until you get to the edge
of the circle, and stop,
and there you have --
now you have divided it --
this upper part into a third,
and truthfully though,
this is actually a sixth
of the graph, okay?
And I'll let you
figure the mathematics
out as far as percentage.
Again, on this side
you would have --
since this is like one-third
of that, or one-sixth
of that whole circle,
this portion is going
to be two-thirds of -- of --
of -- of this portion up here,
or two-sixths, or one-third
of the whole circle.
So if you had to draw
one-third of the whole circle,
that's how you would draw
this segment right up here.
And again, you can keep --
keep this up by remembering that
180 degrees is half a circle,
360 degrees for the
entire circle.
And again, using
your protractor,
along with your Draftsman,
your film, your stylus,
you can draw a circle graph.
