[Edu-sig] Re: easy for beginners, even children

[Gregor Lingl]

Lee Harr schrieb:

>
> For me, it's mostly a matter of "how you say it"
>
>
> How do you say this?
>
> make "a 10
> if :a = 10 [make "a 20]
> ?
>
>
> I guess I would say ...
> make a 10
> if a is equal to 10, then make a 20
>
I would say ...

make a a name for 10
if the object named a equals 10, then make a a name for 20

So you see, that the literal
a
plays a (fundamentally?) different role depending on
if it occurs on the left or the right side of =

In my experience this *is* an important issue when
teaching programming. To understand this difference
*is* a difficulty when learning programming for many students.

And it *is* stressed (and made clear) by the Logo-notation:
"a versus :a  (name versus value)

[Aside: this allows things like the following:

make "a 10
make :a 20
show :a
10
show :10
20                                  

And if you ask: "What the hell, then, is a ?"
You may define it:

to a
output 30
end

show a
30                                                                 ]

So finally we have
"a versus :a  versus a (name versus value versus function-(definition/call))

imho logo is well suited to teach computer science concepts as is
shown, for instance, by Brian Harveys Computer Science Logo style.
This is, because Logo has its roots in  Lisp. (So Harvey also wrote
a well known Scheme book for beginners.)

Nevertheless history has proven, that Logo remains (remained ?)
a teaching - only - language.

Having taught Logo for years I now prefer to use Python as a
teaching language and - indeed  - I think that it easier to
understand and to use (by the students) as soon as problems (tasks)
to be solved get a bit more advanced. (I think this is because then
the Logo syntax becomes a bit clumsy and using lists as
the *only* compound data type is a severe restriction ... (compared
to using dictionaries and user-defined objects)
Shortly: Python is definitely much more "very high level" ...

Regards,
Gregor




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