[MWForum]Creating Fraction Materials

[Lauren Pacini]

Wendy, this is awesome. I just needed the obvious put
in front of me to see how very simple this is!! For a
1/20 Fraction Circle, my code is:

repeat 3600 [pu fd 200 pd rt 90 fd 1 bk 1 pu lt 90 bk
200 rt .1]
repeat (360 / 20) + 2 [pd fd 200 bk 200 rt 360 / 20 ]

Now I will see where the students decide to try to go
with this! The joy of Microworlds! Thanks a million
for unclogging my mind!

I will post their solution!

Lauren

--- Wendy Petti <wpetti@mathcats.com> wrote:

> Wow, this is a great Logo project!  It can certainly
> be done.  I would like
> to make an observation about printing, to start
> with:
> 
> I've developed certain geometric shapes with
> MicroWorlds and posted them on
> the Web.  Depending on whether they are viewed on a
> Mac or a PC at the time
> of printing, they will print out in different sizes.
>  So we cannot give you
> a one-size-fits-all answer to how many pixels = one
> cm when printed.  It
> depends on the computer/printer setup.
> 
> But to start with, your students could run some
> experiments to see how many
> pixels = 1 cm (or 10 cm or 20) cm on *your*
> particular setup.
> 
> The next thing to do is to draw circles with the
> turtle oriented at the
> center point of the circle.
> Don't use this technique:
> 
> to circle
> repeat 360 [fd 5 rt 1]
> end
> 
> There are two problems with that sort of circle:
> 
> 1) You'll end up with short line segments instead of
> a perfectly curved
> circle.
> 2) You won't be able to locate the center point (at
> least not easily) for
> drawing the radii.
> 
> Instead, draw your circle using this approach (the
> examples below will draw
> very small circles; I'm making no attempt to figure
> out the radius you'll
> actually need):
> 
> to circle
> repeat 360 [pu fd 100 pd fd 0 pu bk 100 rt 1]
> end
> 
> However, this will give you a sort of dotted-line
> effect, even for this
> small radius, and moreso as your radius increases in
> size.  This won't
> actually matter if it's only meant to guide you in
> cutting out the fraction
> circles, but there are other solutions if you need
> closed shapes (for
> instance, if you want to fill each slice with a
> different color).
> 
> I've sometimes done this:
> 
> to circle
> repeat 360 [fd fd 100 pd rt 90 fd 2 bk 2 lt 90 pu bk
> 100 rt 1]
> end
> 
> Or you could try this:
> 
> to circle
> repeat 3600 [pu fd 200 pd fd 0 pu bk 200 rt .1]
> end
> 
> or
> 
> to circle
> repeat 7200 [pu fd 200 pd fd 0 pu bk 200 rt .05]
> end
> 
> or the same procedure but using division instead of
> a decimal:
> 
> to circle2
> repeat 7200 [pu fd 200 pd fd 0 pu bk 200 rt 1 / 20]
> end
> 
> Even though the math looks the same, for 1 / 20 =
> .05, the results are
> different.
> 
> In any case, once you've drawn your circle it should
> be easy to divide it
> into slices while the turtle is still at the center
> point:
> 
> to 20-slices
> circle
> repeat 20 [pd fd 200 bk 200 rt 360 / 20]
> end
> 
> You can let the computer do the math for you that
> way.  You can also set up
> sliders to control the size of the radius and the #
> of slices easily.  This
> way you only need one slicing procedure to make all
> the sets of slices:
> 
> (using 2 sliders called radius and #slices:)
> 
> to sliced-pie
> circle
> repeat #slices [pd fd radius bk radius rt 360 /
> #slices
> end
> 
> 
> You'll need to set a large projectsize before you
> get started, for drawing
> circles that are 20 cm in diameter.  And most likely
> you'll need to scroll
> around the project page to see the full circle.
> 
> Good luck, and please let us know how it goes!!!!
> 
> Wendy Petti
> OWL's MicroWorlds in Action
> http://mia.openworldlearning.org
> 
> 
> ...
> > The materials are a series of fractional circles
> with
> > a diameter of 20cm, ranging from 1/2 to 1/20 (180
> > degrees to 13 degrees).
> 
> 
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