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Re: Show left hand side

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  • Subject: [mg111177] Re: Show left hand side
  • From: Helen Read <hpr at>
  • Date: Fri, 23 Jul 2010 07:08:35 -0400 (EDT)
  • References: <i293rl$m8u$>
  • Reply-to: HPR <read at>

On 7/22/2010 5:43 AM, David Park wrote:
> 1) I agree that % and %% are generally a bad idea - except when used within
> a single cell, where they are perfectly all right and convenient.

As I said before, that's a distinction that most beginning students 
won't make. In the beginning they should be putting one input per cell 
anyway, so that they can understand and follow what they are doing. And 
every one of them will jump around and make changes and re-evaluate. Why 
set them up for failure by telling them about % and %% at this stage?

I suppose one could introduce % and %% much, much later, but by then the 
students have learned other, better ways of getting at things. And I 
guarantee that some of them would fail to make the single cell / 
multiple distinction no matter how often, or how well, I explained it.

When I stopped teaching % notation , I stopped using it myself. I've 
gone many, many years without using it, and I don't miss it at all. I 
have never found a good reason to go back to using %, and I don't see 
any compelling reason to teach it.

> 2) Might it be that copying and pasting parts of expressions is an
> error-prone procedure that should be discouraged in favor of using Part or
> Cases or Select.

I'm talking about beginners here. They aren't doing anything where Part 
or Cases or Select is appropriate or necessary. They are copying entire 
expressions, functions, Plot or Table or Solve commands, whatever, 
pasting them in a new cell that may already have other things in it, and 
editing from there. I'm not going to "forbid" or even discourage 
copy/paste -- it would be crippling to the students. But I do teach them 
to separate with semi-colons if they put more than one input in a single 
cell. It's easier to follow, and it avoids potential problems.

> 3) Sooner or later I would think that students would have to use packages.

Not in Calculus 1 and 2. We used to have to load Graphics` and a couple 
of others, but not anymore.

> Why not teach them to have an Initialization section at the top of their
> notebook with Initialization cells for packages and anything else they might
> need? You already teach them to use Sectional organization, which is another
> very good thing in your teaching practices.

I do teach my students to make an initialization section at the top of 
their notebooks, but not until later, and it's not because of using 
packages, but because they are at the stage of writing their substantial 
Mathematica programs.

I have learned a lot about teaching Mathematica from ~15 years of 
experience, and some of what I do for pedagogical reasons may be very 
different from what makes sense to you in your own work.

Helen Read
University of Vermont

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