[etoys-dev] learning algorithms and programming

Ralph Boland rpboland at gmail.com
Fri Dec 23 19:39:01 EST 2011

I want to develop a system for teaching various algorithms
that students learn starting from primary school all the way
to high school and perhaps even into university.
For this I need a core system and for each algorithm an
application layer on top of the core needs to be written.

The idea is the the student first solves the problem by
hand, then implements low level components of the algorithm into
procedures and then is able to solve the problem more quickly by
invoking these procedures by hand.  Then these procedures can be
combined into higher level procedures that the student can use to
solve the problem even more quickly.  Eventually the the entire
algorithm is implemented into a top level procedure that the student
can invoke.

Thus the student learns all the steps of the algorithm (since (s)he initially
does them by hand but also combines them into procedures that can be called
but the student also learns programming at a basic level.  It is
noteworthy that once the student has partially implemented the algorithm
(s)he is able to solve large instances of the problem by using the procedures
already implemented.  For example, a student learning long division could
compute  91935 / 45  more easily after implementing subtraction and
multiplication of a number by a single digit.  The student could then do the
division even faster by implementing a procedure that combines subtraction and
multiplication of a number by a single digit.  And so on.

Algorithms I am interested in implementing include  multiplication,
long division,
simplifying fractions. and simple linear algebra.
I am also interested in Chemistry/Physics and university level algorithms.
For example Gaussian elimination and the simplex method could be
taught this way.

OK so where does EToys fit in?

Well, I don't want to implement this utility from scratch.  But
EToys,  Scratch,
and  BYOB/Snap all implement aspects of what I need already.  Scratch looks
like a better fit than EToys and  BYOB/Snap looks even better (has procedures
and recursion (recursion is useful for simplifying fractions for example)).
Unfortunately for me,  Scratch is being ported to Flash and  Snap is
being rewritten
in Javascript but I very much want to continue working in Smalltalk.
A version of Scratch has been ported to Pharo but the porters suggest
that the best thing to do is rewrite Scratch from scratch since it is
so poorly written.

So my question is: Would it be better to use the core of EToys to
build my system.
For that matter, if I wanted to re-implement Scratch should I not use
the core of
EToys to base it on?  This probably means that EToys would need to be
to some extent so that a core could be separated from the "EToys Application".
In fact, I might need a Scratch/Snap core that goes on top of  EToys core.
For that matter should not EToys and Scratch already have been written with
a common core?

For those of you familiar with the Enchanting project (which allows programming
of the Legos Mindstorms robot using a version of Scratch)  I would
also want to be
able to base Enchanting on the core of EToys.  By the way Enchanting
is an example
of where a web based version of Scratch is not going to work so it
looks like Enchanting
developers will have to maintain their version of Scratch.

So what should my plan be?


Ralph Boland

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