


27 July 1998 Vol. 3, No. 30
THE MATH FORUM INTERNET NEWS
Project Interactivate | JavaSketchpad | Geometry Software/Theory
PROJECT INTERACTIVATE - The Shodor Foundation
http://www.shodor.org/interactivate/
Project Interactivate is part of the Presidential Technology
Initiative. The materials it develops are designed to be
adapted easily to any NCTM Standards-based middle school
mathematics text.
Middle school lessons cover probability, statistics,
functions, and fractals:
http://www.shodor.org/interactivate/lessons/
Discussions on these subjects range from the probability
of simultaneous events and introducing elementary set
operations through Internet search, to histograms vs. bar
graphs and recursion in fractals:
http://www.shodor.org/interactivate/discussions/
Applets that provide computer simulations present
opportunities for group work as well as individual
investigation.
http://www.shodor.org/interactivate/applets/
Explorations offered by Project Interactivate include:
- Monty Hall, three doors
- Stock Exchange
- Linear Regression
- Normal Distribution
- Gnuplot
- Random Function Machine
- Hilbert Curve Generator
- Sierpinski Carpet Generator
- Pascal's Triangle - Multiples, Remainders
- Fire!!
... and many more.
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JAVASKETCHPAD - Key Curriculum Press
http://www.keypress.com/sketchpad/java_gsp/
JavaSketchpad is software that lets you interact with or
publish sketches from The Geometer's Sketchpad on the Internet.
(The Geometer's Sketchpad is a dynamic geometry exploration
environment available for Macintosh and PC computers from
Key Curriculum Press.)
JavaSketchpad can be used to share geometry work with people
who may not have desktop Sketchpad or who use computers
(like most Unix machines) that can't access it; or to
distribute interactive dynamic geometry activities and
curriculum over the Internet. Advanced users, programmers,
and mathematical researchers can use the program to add
dynamic geometry visualization to other software or problem
contexts.
See the JavaSketchpad demo gallery for some examples of
JavaSketchpad in use.
http://www.keypress.com/sketchpad/java_gsp/gallery.html
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JavaGSP! - Annie Fetter
http://mathforum.org/workshops/sum98/java.gsp.explain.html
A short tutorial: everything you need to know to make your
first JavaSketchpad page. A quick reference is followed by
other features, details, and considerations: what you need,
what you do, what works, and what doesn't.
Examples include Drawing a Solid and Its Net; Investigating
Parallelograms; and Identifying Polygons.
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GEOMETRY DISCUSSIONS: SOFTWARE AND THEORY
GSP INTERSECTION OF A SEGMENT AND A LINE
Dave Wilson and Nick Jackiw
A geometry-software-dynamic discussion
http://mathforum.org/epigone/geometry-software-dynamic/zouyybrel
http://mathforum.org/epigone/geometry-software-dynamic/shunkunho
http://mathforum.org/epigone/geometry-software-dynamic/smolstugou
"... GSP shows this point on the screen when
the lines are visually not parallel... a quick
measurement of the angle shows that the lines
are 3 to 5 degrees out. GSP measures the
distance from the constructed midpoint to the
the parallel line through B and reports a
non zero distance whilst displaying the point
of intersection. A bit of a contradiction."
- Dave Wilson
"Dave has put together a construction that reveals
an inherent limitation in floating point number
representation, and even... conflicts with special
purpose code embedded in Sketchpad that attempts
to circumvent these limitations in typical cases.
As Dave writes, the result is that, under this
construction, Sketchpad incorrectly displays a
point at intersection when none theoretically
exists...." - Nick Jackiw
A discussion of floating point representation and exact
arithmetic as these affect Sketchpad construction issues.
Nick Jackiw also poses and explores some interesting
questions:
(1) What is the desirability of a proving system
integrated with a dynamic geometry program?
(2) Lacking proof-integrated systems, how do you handle
the inevitable problems of rounding in construction
and metric inaccuracies in the classroom?
(3) What sort of workarounds are available?
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The Theme of the Letter:
PROOF AND PERCEPTION II - Michael Otte
(From PREUVE PROOF PRUEBA, the Web Newsletter)
http://www-cabri.imag.fr/Preuve/
"In the July/August issue of the Proof Newsletter,
Michael Otte from Bielefeld offers some thoughts
on Geometry and mathematical proof. The newsletter
is open to reactions and comments."
- Nicolas Balacheff, Editor
"Mathematics as a form of relational thinking is not
concerned with objects or their properties as such, and
neither with relations between objects in themselves,
but rather with relations between possible objects of
activity.... Mathematics, and in particular axiomatized
mathematics, considers objects only with regard to the
consequences they might have for the process of
mathematical reasoning...." - Michael Otte
The goal of "The Theme of the Letter" is the stimulation
of exchanges on current questions about the learning
and teaching of mathematical proof. This contribution
by Michael Otte is a continuation of text published in
the Jan./Feb. 1998 issue of the Proof Newsletter.
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