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<div class=Section1>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>My experience with turtle graphics in a
CS1 course has been very rewarding. It allows *<b><span style='font-weight:
bold'>everyone</span></b>*, not just the most motivated, to be creative. With
turtle, drawing an original and intersting design is so easy. In a couple of dozens
of lines, my CS1 students create some amazing designs – every semester
brings more and more gems. Students use turtle to draw fractals and then concentric
figures that change colors and are constantly redrawn. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Of course, turtle is not fast and it is
not fancy as programming, and it behaves badly in Windows, but the important
thing is that it really inspires almost all beginners to learn and do more. My students
post their turtle graphics designs in course Forums and they are so proud –
for good reason. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Consider for example this simple program:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=SV
style='font-size:10.0pt;font-family:Arial;color:navy'># Pattern Designer<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=SV
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>import turtle;<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'># Create a blue pen and determine the
window's width and height:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>def init():<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> pen = turtle.Pen();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> pen.color(0, 0, 1); # blue<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> width = pen.window_width();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> height = pen.window_height();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> return pen, width, height;<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'># Given a number, design a pattern for
that number:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>def pattern(number):<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> pen, w, h = init();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> # Switch off tracing for higher speed:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> pen.tracer(False); <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> for x in range(-w/2, +w/2):<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> for y in range (-h/2, +h/2):<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> draw(pen, number, x, y);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> # Temporarily switch on tracing to
observe drawing:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> if (x % 100 == 0):<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> pen.tracer(True);
pen.tracer(False);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> pen.tracer(True);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'># Draw a pattern element at point (x, y):<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>def draw(pen, number, x, y):<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> a = y * (number / 100.0);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> b = x * (number / 100.0);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font><font size=2 color=navy
face=Arial><span lang=PT-BR style='font-size:10.0pt;font-family:Arial;
color:navy'>ez = int(a*a*a + b*b*b); <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=PT-BR
style='font-size:10.0pt;font-family:Arial;color:navy'> </span></font><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'># Try ez = int(a*a + b*b) and other expressions.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> if (ez % 2 == 0):<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> pen.up(); pen.goto(x, y);
pen.down();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font><font size=2
color=navy face=Arial><span lang=IT style='font-size:10.0pt;font-family:Arial;
color:navy'>pen.circle(1);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=IT
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=IT
style='font-size:10.0pt;font-family:Arial;color:navy'># Draw pattern #5<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=IT
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>pattern(5);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>#<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The above program is a framework to design
original patterns that are different form anything else – just by playing
with the draw function above. Change the expression that defines ez, use random
numbers for colors, etc. The opportunities for creative designs are unlimited.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Of course the above program is slow. But
it delivers exciting designs and inspires people. This is what matters,
particularly in CS1.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Certainly, one can use more realistic
platforms, such as VPython, but then the complexity will probably kill the
enthusiasm. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>This is why I am interested in the turtle
module and its improvement. (Thank you again, Vern.)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Atanas<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=SV
style='font-size:10.0pt;font-family:Arial;color:navy'>Atanas
Radenski <br>
</span></font><font size=2 color=navy face=Arial><span style='font-size:10.0pt;
font-family:Arial;color:navy'><a href="mailto:radenski@chapman.edu"><span
lang=SV>mailto:radenski@chapman.edu</span></a></span></font><font size=2
color=navy face=Arial><span lang=SV style='font-size:10.0pt;font-family:Arial;
color:navy'> </span></font><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><a href="http://www.chapman.edu/~radenski/"><span lang=SV>http://www.chapman.edu/~radenski/</span></a></span></font><font
color=navy><span lang=SV style='color:navy'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=navy face="Times New Roman"><span
lang=SV style='font-size:12.0pt;color:navy'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#383838" face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New";color:#383838'>I find
television very educating. Every time somebody turns on the set, I go into the
other room and read a book - Groucho Marx</span></font><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'><o:p></o:p></span></font></p>
</div>
<div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'>
<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
</span></font></div>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
edu-sig-bounces@python.org [mailto:edu-sig-bounces@python.org] <b><span
style='font-weight:bold'>On Behalf Of </span></b>kirby urner<br>
<b><span style='font-weight:bold'>Sent:</span></b> Tuesday, February 28, 2006
5:10 PM<br>
<b><span style='font-weight:bold'>To:</span></b> Toby Donaldson<br>
<b><span style='font-weight:bold'>Cc:</span></b> edu-sig@python.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Edu-sig] Edu-sig
Digest, Vol 31, Issue 16</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>On 2/28/06, <b><span style='font-weight:bold'>Toby Donaldson</span></b>
<<a href="mailto:tjd@sfu.ca">tjd@sfu.ca</a>> wrote:<o:p></o:p></span></font></p>
<div>
<blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;
margin-left:4.8pt;margin-right:0in'>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
1. The broken interaction between Idle and the turtle package.<br>
<br>
2. Poor documentation. To actually understand certain function<br>
calls, it was necessary to read the turtle.py source code.<o:p></o:p></span></font></p>
</blockquote>
<div>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
My tentative conclusion, reading the above, and from some personal experience,
is the Tkinter turtle.py, while a fun demo, is mostly a toy and should not be
used for serious teaching, at least on Windows. Too much adverse experience.
Too much frustration. In general, Tk on Windows has a lot of problems --
I generally forsake IDLE and go to a command window, for good reason.
IPython is an alternative (a good one -- once you get it working in Windows,
which is very doable). <br>
<br>
I really don't think *any* kind of turtle graphics is essential to learning
programming, although as I said, I think the approach is very viable and
destined to last. I'm not "anti turtle".<br>
<br>
My own special interest is in going back to the very early days of Logo, when a
physical robot was used. I'd rather have hardware robots than screen
based ones, with Python bindings. SONY should seed me a prototype :-D <br>
<br>
Kirby<o:p></o:p></span></font></p>
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