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Re: [Maxima-discuss] A question about parsing: ":lisp #$expr$" is not low-level enough
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From: Raymond T. <toy...@gm...> - 2022-01-15 18:27:06
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On Fri, Jan 14, 2022 at 2:10 PM Barton Willis via Maxima-discuss <
max...@li...> wrote:
> > If (as is the case with many schools) there is a student survey after
> the class is over, how will students react to questions about the
> additional material?
>
> *Additional wandering:* For eight years, I served as a department chair
> for a faculty of about fifteen at a hyphenated public university. As chair,
> I saw 1000s of student evaluations and comments. Asking students to do
> anything "unusual" (use TeX, explain something using two sentences, or
> use a programming language in a course on statistics) is a fairly clear
> path to lower teaching evaluations. I know this might seem cynical and I
> know that humans are subject to huge amounts of confirmation bias, but I
> informally collected this data.
>
Interesting. I was very happy to use SPSS or whatever it was in my stats
class in college. I hated doing ANOVA and stuff like that by hand.
>
> Generally, I do not reveal to students that I sometimes contribute to an
> open source computer algebra system, and that I donate a bit of my time
> helping people around the globe to use it. I teach a fairly traditional
> calculus class.
>
> As for cheating during an online math exam, it's the second pandemic. Of
> course, we can simply change our notion of cheating. A popular option is
> to mostly abandon exams in favor of experiential learning, group work, and
> activities. We like to ignore the fact that academic research shows that
> group work often puts introverts at a disadvantage.
>
I generally hated group work. Perhaps because I'm a bit introverted, but
mostly because everything took much longer than it should have.
At my college we had self-study classes supposedly to let students learn at
roughly their own pace and perhaps help them do better. There were still
tests, and you had to finish a certain amount of material. I just tried to
go as fast as possible and learned just enough to get a good grade. (You
can retry different tests as many times as needed, with a delay between
retries). I think in the end, I ended up cheating myself because I didn't
remember anything afterwards. Fortunately, these classes weren't really
required for later classes (or at least the classes I ended up taking
later).
>
> Some say that they can construct questions, such as tell me the next step
> in the calculation, to combat cheating on online exams. I don't think this
> is a particularly good solution--my steps might not be your steps. And
> unless the long list of questions at the end of each section are changed to
> tell-me-the-next step variety, I think it's not a fair way to test
> students.
>
> --Barton
> ------------------------------
> *From:* Richard Fateman <fa...@gm...>
> *Sent:* Friday, January 14, 2022 14:57
> *To:* Eduardo Ochs <edu...@gm...>
> *Cc:* <max...@li...> <
> max...@li...>
> *Subject:* Re: [Maxima-discuss] A question about parsing: ":lisp #$expr$"
> is not low-level enough
>
> Non-NU Email
> ------------------------------
> This is going to wander quite a bit from the original question, but here
> goes.
>
> We see proposed usages like Eduardo's from time to time, and there are
> more or less a bunch of questions that come up, especially
> in the context of enthusiastic teachers assuming technology is good for
> the students. So here are some
> thoughts.
> 1. It is possible to use Maxima and similar programs as essentially
> typesetting assistants. That is
> you type something in, and you get something displayed. The fact that you
> type in a+x and it displays
> x+a is unacceptable, and so you start on workarounds. Some people use
> "a+x" or turn off simplification etc
>
> This can work, but it MAY miss a significant point or two. These have come
> up previously, and the
> answers are kind of squirmy.
>
> 2. what part of your curriculum is 'students learn the input syntax of a
> computer algebra system';
> 'students become proficient in typing mathematics [on a phone:? on a
> keyboard?]
>
> 3. And if a student asks,
> 'Is this going to be on the final?' you might have to say, no, there will
> be no computers then.
>
> 4. Beyond the input syntax issue, there is 'what does it mean to
> evaluate/substitute/simplify ... in the context of
> a computer algebra system? Is this on the final?
>
> 5. if a computer can do differentiation, integration, solve equations,
> plot functions... why should I have to
> do this? Isn't this showing that this course is even more unimportant that
> I thought?
>
> When I taught a calculus+ computer algebra course many years ago, the
> students were far more curious about
> how the computer did the integration problems than anything else. These
> were high-end students though.
>
> Low end students will, most likely, want to get a passing grade in
> calculus with the least effort, and then will
> thoroughly forget whatever material they absorbed. They may also be
> inclined to cheat, especially when
> examinations are so hard to proctor over zoom. If (as is the case with
> many schools) there is a student survey after the class
> is over, how will students react to questions about the additional
> material? They have enough trouble with
> understanding what a "function" is, without being confused by computer
> languages and such. So they may give
> the instructor (you...) a low rating.
>
> There is a scant literature on this, and I haven't looked at it in some
> years, but when the question is posed as to
> whether students learned calculus better with a computer lab, the answer
> has been: no, they did not learn
> better. No, by and large they did not enjoy the (substantially enriched)
> technical material. Maybe there is
> different evidence today in support of using computers. Maybe it is
> possible to run a course without a human
> instructor -- just "learn calculus in 25 easy lessons, online"?
>
> It is not my intention to discourage people from trying innovative ideas
> so much as to look at them critically.
> "Putting it on the computer" is not always a win.
>
>
> oh, two quick items:
> v:a+x$
> ?subst(43,a,v); ==> x+43
>
> ?subst( 43,x, x + 'integrate(f(x),x)) ==> integrate(f(43),43)+43
> which is, logically, bonkers. The x inside integrate is a 'bound
> variable'.
>
> If you want to teach this, good luck. Is it related to "what does the
> 'd' mean in integral(f dx) ? And what does the space between f and d mean?
> Is it multiplication?
> Have fun.
> Cheers
> Rjf
>
>
>
>
>
>
> On Thu, Jan 13, 2022 at 10:00 PM Eduardo Ochs <edu...@gm...>
> wrote:
>
> Nifty!!!!!!! =) =) =)
>
> My use case is very atypical. In my classes I have many students who
> have very little practice with using variables - really! It's sad &
> scary - and when these students have to take a formula and perform a
> substitution on it to obtain a particular case they usually make a big
> mess... for example, they often substitute only certain occurrences of
> the variables, and leave the other ones unsubsituted. And when they
> have to perform substitutions on theorems, propositions, or proofs the
> mess is even bigger...
>
> So: I'm trying to teach them that substitution and simplification _can
> be treated_ as separate operations, and when we keep them as separate
> steps our calculations become much easier to debug... We're doing that
> on paper, and I told them that I believe that all decent programs for
> Computer Algebra should be able to perform substitution in a purely
> syntactical way, without simplification, _if we call the right
> low-level functions in them_. With your trick I'm almost there... try
> this:
>
> simp:false;
> to_lisp();
> (defun $displr (lambdaexpr) (displa (caddr lambdaexpr)))
> (to-maxima)
> q: lambda([foo], ('integrate(f(x), x, a, b) = F(b) - F(a)));
> displr(q)$
> displr(subst([a=42, b=99], q))$
> displr(subst([a=42, b=99, f(x)=3*x^2, F(x)=x^3], q))$
> displr(subst([a=42, b=99, f(x)=3*x^2, F=lambda([x],x^3)], q))$
>
> In the last two lines I'm trying to replace all occurrences of F(expr)
> by expr^3, but I haven't found the right trick yet...
>
> Cheers and probably thanks in advance =),
>
> Eduardo Ochs
> http://angg.twu.net/eev-maxima.html
> <https://urldefense.com/v3/__http://angg.twu.net/eev-maxima.html__;!!PvXuogZ4sRB2p-tU!Uiy9-wA6d-agkixNbW5Pr5RtNxWANcdbjDny63-pmyVEanMZ6muQnFAuKjQlmas$>
>
> On Thu, 13 Jan 2022 at 11:11, Stavros Macrakis <mac...@al...>
> wrote:
>
> Simplification does not happen as a separate step after evaluation of the
> whole expression.
> Every subexpression that is evaluated is immediately simplified. Maxima
> couldn't possibly work otherwise.
>
> Obviously we need to be review our documentation more carefully to keep
> such howlers out!
>
> Using :lisp #$ ... $ seems pretty roundabout. To turn off simplification,
> set *simp:false*. To prevent evaluation, use *'( ... )*. To show the
> internal form of something, use *?print(...)*.
>
> Here's a neat trick: within *lambda* expressions (as well as named
> function definitions), neither simplification nor evaluation is performed,
> so *q: lambda([simp], ?print(2+2)) *might help you see how things work;
> look at *q*, and call *q(false) *and *q(true)* .
>
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--
Ray
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