Re: [Maxima-discuss] A question about parsing: ":lisp #$expr$" is not low-level enough

[Eduardo O. <edu...@gm...>]

 Hi all,

ok, let me try to explain how and why I am using Maxima in my
classes... I'll have to start with a lot of context, as I'll have to
talk about several different groups of people...


Part 1: the groups that I interact with
=======================================

One of the biggest federal universities in the state of Rio de Janeiro
is called (the) UFF. The main campus of the UFF is in a (big) city
called Niterói, that is very close to Rio de Janeiro (the city - even
bigger than Niterói). The UFF has several campi in other cities, and I
work in a small campi in a (small) city called Rio das Ostras.

Bolsonaro has cut the funding for education at all levels as much as
he could, including the funding for the top universities and for the
top research institutes, that were treated as sacred in the other
governments. On top of that the pandemic came. Several universities,
including UFF, were already having to negotiate a lot every month to
get money to pay basic things like electricity and water, and the
cleaning and the security staff, and when the quarantine started the
message that we received was more or less this: "we know that most of
you have never learned how to so online teaching, so now we will give
you four months to prepare - try to do some courses, and do your best.
This is an emergency, we know that everybody will have to improvise a
lot, etc, etc."

I knew that teaching by Zoom wouldn't work for me because in my
courses I always interact a lot with the students _via writing_ - when
they have doubts I prefer to see how they are trying to write and draw
their ideas rather than to hear them - so I invented a way to teach my
courses in which most of the interaction would be by Telegram, with
people exchanging photos of what they were doing... I would often
LaTeX my ideas and answers instead of writing them by hand on paper,
but that's because I've been using LaTeX for ages and I'm quite fast
with it.

This "teaching by Telegram" thing worked very well. I also used
prerecorded videos, slides in PDF, and a few bits of material by other
people, but I'll refer to that as "teaching by Telegram".

In the middle of 2020 I discovered that a group of about 30 people
from several universities in Brazil were going to meet by Zoom once
every two weeks to discuss mainly a) how do teach online, and b) how
to adapt the contents of some courses to a context in which the
students can use computers to plot graphs and to do some calculations.
Let me call this group the "inter-university group", or the "IUG".

Actually I "discovered" the IUG because one of the organizers was a
friend of mine, and he invited me to participate. At one point I
offered to present how I was "teaching by Telegram", and in one of the
meetings I gave a talk about that, and I showed that all my material
was online - including all the parts in which I presented things in
ways that didn't work, or in which I gave exercises that I had to
change completely later. My presentation was very well-received, and I
found some people there who were also trying to make all their
material available in public places.

So we have three groups:

  UFF - big campus in a big city
  Rio das Ostras - small subcampus in a small city
  Inter-university group, a.k.a. IUG

The people from my department in Rio das Ostras did try to meet by
Zoom to discuss online teaching a few times, but we were only able to
arrange these meeting at most once every semester. We are a small
department, and it seems that each person is trying something totally
different - and everyone is reporting that the students participate
very little, that in most classes by Zoom/Google Meet/whatever very
few students keep their cameras open, and that cheating is rampant
even with their all attempts to make cheating harder... for example,
some of my colleagues learned ways to give a slightly different test
to each student, and learned features of Google Classroom that makes
it auto-correct some kinds of tests, but nothing is working.

Before giving my presentation on "teaching by Telegram" at the IUG a
gave a preliminary version of it in one of these meetings of my
department - in which very few people came - and it was well-received.
Then after my presentation at the IUG I sent the link with the
recording to my dept's mailing list, and some people in my department
FREAKED OUT. They reacted very angrily - I've reread their e-mails to
the mailing lists many times after they were sent and they still don't
look very coherent to me, so I think that "freaked out" is a good
term, at least until I find something better.

So: I was hoping that the people in my department would look at my
material, find some interesting things here and there, and react by
sharing pieces of their own teaching materials and sharing ideas...
now I think that the chance of this happening is small.

A friend of mine from Rio das Ostras is temporarily working at UFF -
the big campus, with big teams teaching each of the basic courses in
Maths - and I asked if he could share with me the material that the
people there use in Calculus 1, 2, and 3. He checked with his
superiors and told me that no, there is a kind of non-disclosure
agreement.

SUMMARY OF PART 1: interacting with the colleagues in my campus is
very hard at the moment, and interacting with the people in the big
campus of UFF is very hard too. So my priority is to interact with
people from the IUG in Portuguese, and with other people from the
internets in English.


Part 2: students
================

Many of my students have very bad internet connections, and bad
computers that they share with other people - so very often they can
only use their cell phones to participate in the classes. But some
other students have, aham, "real computers" - even in this sense:
https://dilbert.com/strip/1995-06-24 - and when they see that I have a
couple of Free Software projects that I take very seriously and that I
am learning to use Maxima (<- was SymPy before, but I gave up) they
ask if I can teach or help them to use these things. My answer is -
ta-da! - yes, but not during class, so let's create another Telegram
group for that. And right now this other Telegram group is dead, the
last message in it was more than a month ago.

Here's an incomplete list of how the students see that I am using
Maxima in the classes that I am teaching. I am using Maxima for some
2D and 3D plots; I am using it to calculate the answers to certain
exercises - for example here:

  http://angg.twu.net/LATEX/2021-2-C3-notacao-de-fisicos.pdf#page=26

so if they want to check the answers that they got by hand they will
have to decypher this slightly obfuscated notation; I am using it as
one of my excuses to stress ALL THE TIME that BASIC mathematical
notation has a very rigid syntax - each one of the books that we use
has slightly different conventions, and Maxima and GeoGebra (that some
of them learned in a previous course) use other syntaxes that are
quite different - and that in my course syntax errors will not be
tolerated...

I am having to deal with several epidemics here - besides Covid,
cheating, and lack of focus, we also have an epidemy of students that
believe that an answer to a test HAS to receive full grade, or almost,
"if the idea is right". I don't know how much this last one affects
other countries - I would really like to know - and I try to deal with
this last one by having a ton of material on how to write answers
"that everyone understands"...

I don't have any idea how my colleagues in my department, or in the
big campus, deal with the epidemy of "if the idea is right that's
enough" - I don't have enough social skills to get answers from them -
so I am sort of trying to get some people from the IUG to share the
materials on that they have, both in Portuguese and in English... and
they're answering very slowly.

About the low-end students: they don't interact, they cheat on the
tests, they're hard to distinguish from the students that are just
very introverted, and _right now_ I don't have the tools to detect
when they're cheating. My resources are limited, we're in an
emergency, I'm doing my best, and this includes that I'm choosing
carefully where to I will invest my energy... and I chose to invest it
on the students who interact, and on producing written material can be
useful to me and to the other people from the IUG in this semester and
in the future...


Part 3: substitution
====================
This is mostly an answer to this message,

  https://sourceforge.net/p/maxima/mailman/message/37417646/

that Richard sent on jan. 14...

Every semester I change my approach to substitution a bit. In this
semester I defined an operation "[:=]" that does substituition
"syntactically" and "naively". The "syntactically" means that the "="
after a substituition is special - it means "the result of this
substitution, WITHOUT ANY SIMPLIFICATIONS, is the expressions at the
right of the equals sign"; so these two lines are right,

  (2 = 3 + a * 4) [a:=5]   = (2 = 3 +  5    * 4)
  (2 = 3 + a * 4) [a:=5+6] = (2 = 3 + (5+6) * 4)

but this one is wrong, because in it the 10*4 was simplified to 40:

  (2 = 3 + a * 4) [a:=10]  = (2 = 3 + 40)

The explanation that I showed to the students is this one - that only
exists in Portuguese at the moment...

  http://angg.twu.net/LATEX/2021-2-C2-intro.pdf#page=8

I also stressed to the students that my "naive substitution", that was
"defined" by text and examples instead of rigorously, and that doesn't
distinguish between free and bound variables, will be enough for our
purposes - and that to understand the "better" substitution operations
they will have to understand free and bound variables well, and free
and bound variables will make much more sense at the end of the couse,
after they were forced to work a lot with sums, integrals,
quantifiers, and set comprehensions.

The first time that I got feedback from an "adult" on this naive
syntactical substituion was just a few weeks ago, from a colleague
that is a logician and who works in a university in the Northeast of
Brazil. He liked it very much as a pedagogical tool, and he also told
me that he's having more or less the same difficulties to deal with
his colleagues as me. Anyway, now I finally have good excuses to write
about that in English - but it's a low-priority task. =/

  Cheers,
    Eduardo Ochs
    http://angg.twu.net/#eev
    http://angg.twu.net/eev-maxima.html
    http://angg.twu.net/math-b.html