Mailman 3 February 2000 - Edu-sig

Rational Division
by Jeffrey Kunce Feb. 5, 2000

Feb. 5, 2000

Smalltalk has a subclass of "Number" called "Fraction". When you write 2/3 in Smalltalk, it actually stores the numerator and the denominator, and the whole roundoff question is moot. (Of course there is a protocol for mixed-mode arithmetic.) I taught Smalltalk to a number of programmers, and this was always a difficult feature. The "integer vs real" dichotomy is so engrained in the programming culture that it was hard to accept a different representation. Usually, once I reminded them about their high school algebra classes, and how they dealt with fractions in equations, the concept would fall into place. So, what does "E" think? Does 2/3==0 or does 2/3==1 or does 2/3=0.66..67 or does 2/3==2/3? I'm not saying that "E" thinks of 2/3 as a rational fraction, but I think we ought to do some asking before we decide on something else. --Jeff

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RE: [Edu-sig] More Lesson Planning (correction)
by Kirby Urner Feb. 5, 2000

Feb. 5, 2000

>not-the-answer-you-asked-for-but-hope-it-was-interesting- > anyway<wink>-ly y'rs - tim On the contrary, this was _exactly_ the kind of answer I was hoping for. Very lucid and elucidating oh Mr. Python guru sir. Sincerely, Kirby

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inspecting a special world: the computer
by L. Humbert Feb. 5, 2000

Feb. 5, 2000

Hi, please excuse my english, I learned it at school many years ago (;- Let me introduce myself: I'm a teacher in informatics (this is sligthy different from CS). Before prepared to teach informatics, I studied informatics in general. In teaching, I began to _teach_ concepts in schools using several programming languages: - Pascal (and not BASIC), - Modula-2 (and not Pascal), - I took a look at Oberon-2, but the computers in school couldn't run it - Python (and not Oberon-2), - JPython (and not Java) in secondary school (K-13) for beginners in their 11th year in school. I know, it is very late, but at this moment there is no way to teach informatics for all students in secondary I - schools. What do you want to teach? -------------------------- my credo: o Programming -- no, o [perhaps] Solving problems -- even better, o modelling -- that's quite good, I think. case InSeNsItIvE? -- No! ---------------------- In my opinion the case sensitive construction is ok. - not only for me, but for my students, because they are teached to regulary write case-sensitive in my country. I never had problems with this in the beginning courses, the 2nd reason maybe, I told them not only the difference, but the advantage of this decision. But you have to consider: I'm a german and in my language nouns are written with a first uppercase character. So, when modelling objectoriented, the students learn how to analyse and how to write classes, methods and attribute (classes are nouns --> 1st character uppercase, ...) So I beg you: tell your students, that and why this decision makes sense and without sense, they never will be able to understand other levels of clean abstraction. platform dependend -- No! -------------------------- The last years of working as teacher I had to teach young assistent-teachers to become teachers. This way I became a look insight other schools: different platforms, different languages different examples, differnt curricula, ... So, this is a must: schools need software, running on the Mac, on Linux and of course on Win. You may construct and evaluate prototypes - running only on one platform, but if we want to go into "production", we need software, which runs on all of the above mentioned OS. Why JPython? ------------ I'm a teacher with low time capabilities in modelling (and implementing) a _paedagogical_ well defined class-structure for my students. Some years ago, several teachers sat down and constructed a class-library for teaching objectoriented concepts rather than languages. We implemented the class structure for some Pascal-dialects, Oberon-2, and later on Java. In the meantime, the material for teaching this concept is available (but it's written in german). Find some information http://region.hagen.de/OOP/#PYTHON At this location you find a link to: SuM.jar (this includes all the classes you need to work) So you are able (if you installed JPython), to test the beginners example, I give at the bottom of this mail. In the meantime, the material is published (but again: it's in German): (Czischke1999,EDITION) = 1.~Ed. (Czischke1999,PUBLISHER) = DruckVerlag Kettler GmbH (Czischke1999,YEAR) = #1999 (Czischke1999,EDITOR) = {Landesinstitut f{\"u}r Schule und Weiterbildung} (Czischke1999,ADDRESS) = B{\"o}nen (Czischke1999,REFTYPE) = book (Czischke1999,ANNOTE) = ISBN 3-8165-4165-8 (Czischke1999,TITLE) = Von Stiften und M{\"a}usen (Czischke1999,AUTHOR) = J{\"u}rgen Czischke and Georg Dick and Horst Hildebrecht and Ludger Humbert and Werner Ueding and Klaus Wallos My way to JPython: in JPython I am able to use the SuM.jar and the students too. 1. The students work with the JPython-console interactive (on iMacs). They learn how to import and use classes, for working on "the screen". opening a window, drawing on it with some method-call, etc. They are told how to "explore" a given class: dir(classname) or package: dir(packagename) 2. the first classes in this package (SuM.jar) are: Bildschirm, Tastatur, Maus, Stift [later extended to BuntStift] and some more. The students themself identify the components of their actual computer environment and point out, what methods should be realized. They are able to inspect this by looking at the classes. The classes are handy, easy to use and so you can concentrate on concepts instead of syntactical constructions. The JPython interactive environment is - for my students - the frontend for testing. Ok: they have to learn how to use an editor (in our special case it's BBEdit) and to save their work. But isn't it easy to type _and_ evaluate interactive? Example: >>> from stiftUndCo import Bildschirm >>> from stiftUndCo import Stift >>> meinBildschirm=Bildschirm() # you see the window coming up >>> meinStift=Stift() >>> meinStift.runter() >>> meinStift.bewegeBis(320,240) # you see the line getting drawn >>> meinStift.zeichneKreis(30) # ... It's a turtle based geometry, with some more methods for absolute placing. This way students learn, how to control components in this environment. They learn to interactive control the scene by the mouse (class Maus) and keyboard (class Tastatur). In this way, you teach control structures, as they are needed. One day they'll ask: why can't we use some color and you have to teach that there are some more classes: at first BuntStift, --> here you have to explain, what subclassing is good for. BuntStift is an extension of Stift ... I'll stop here in describing. This is not the place to show the whole course. In some months, I'll hope to be able to put some material online, so you can get it by using the URL http://region.hagen.de/OOP/ At the moment, the material for my course is only online in the intranet of my school (using a local BSCW-Server, which was writen in Python). L. Humbert humbert(a)hagen.de

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Re: [Edu-sig] Getting it going
by Dirk-Ulrich Heise Feb. 5, 2000

Feb. 5, 2000

Hi! Like Steve Morris, i have a kid and that's why i'm here. I will create programs he can abuse anyway over the time, so let's see what the others do. So, i'm interested in "teaching programming to absolute beginners." As kids learn fast as long as they have fun, a main objective is to define goals that are fun. Every now and then when i tried to explain programming to an adult programming illiterate, they would roll their eyes and say something like: "But *why* do you do it?" or "Why should i want to write a program?" So, i go conform to the "sound&vision" ideas like "control a 3D world" or "make noise". 2D animations could also be interesting, the maths behind it is much easier to grasp. So much for now. Dirk Heise

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a modest proposal
by Steve Morris Feb. 5, 2000

Feb. 5, 2000

Let me suggest that the goal be restated. Rather than teaching programming to the masses perhaps the goal should be to teach the masses to solve various problems using programming. Maybe I am picking nits here but many of the success stories here and otherwhere seem to come from projects that had specific problems that they wanted the student to solve and programming happened to be the convenient (sometimes the only possible) approach. I think if we focus more on a problem solving framework the needs of the IDE and language come into better focus. What I would like to see is a framework which presented a programming "world" probably with an easily visible (browsable) set of classes and objects which more or less defined that world, maybe a workspace concept. In otherwords the user should be able to "enter" one or more worlds, each of which defined a problem space. The worlds would be "explorable" in some way. Properties of objects would be discoverable by examination and experimentation. Simple behaviors would be simple to invoke. More complex behaviors would be possible as a simple progression. To me making this kind of world is key. Standardizing this kind of interface so that people could create worlds/problem spaces/applications as extensions to the system would makes its use grow. Various contributors would add different worlds and the thing would grow. Am I way off base? I think jumping into the nitty gritty of things like case sensitivity puts the cart before the horse. We need to make sure we are solving the right problem.

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FW: [Edu-sig] Getting it going
by David Scherer Feb. 4, 2000

Feb. 4, 2000

> > I've also found at the conference that there are already at least half > > a dozen serious IDEs (interactive development environments) for Python > > in existence or under development. I still want to continue to use > > IDLE to experiment with some advanced features (such as syntax > > checking while you type), but I think it's important that the > > classroom materials allow the choice of different IDEs -- if only > > because not all IDEs work on all platforms, and we do need to support > > Windows, Mac and Linux! This may be appropriate in the very short run. However, I think that a completely cross-platform IDE suitable for novices needs to be developed, packaged with everything that will be needed for novice users in an absolutely airtight installer for every platform, and distributed with tutorials and course materials. Programmers are conditioned to believe that the lexical content of a program is everything, and that the programming environment is secondary. This is just not the case. To draw an analogy from an introductory Psych course I once took: when scuba divers are taught factual information ("What should the pressure in your oxygen tank be?") in a classroom and then tested underwater, they perform poorly. If they are taught underwater and tested in the classroom, they perform poorly. If they are taught and tested underwater, they perform well! Environment is at least as important as syntax in ease-of-use for beginners. Further, students should be able to work in the computer lab at school and their computers at home in a consistent environment. Another issue is that the IDE needs to be absolutely stable. IDLE and most other Python IDEs share a single Python interpreter with the user program. I am convinced that this architecture is unacceptable for novice users (and for me!) A program like: while 1: pass executed in the console-mode python interpreter, can be easily stopped with control-break. The same program in IDLE will cause the editor to freeze, possibly destroying unsaved changes, and force the user to use OS-level mechanisms to kill the process. The single-interpreter architecture also causes problems running programs that access the same libraries (e.g. Tk) as the IDE. Features like symbolic debugging are much harder if the user program runs in a separate process, but I think that stability needs to take priority. > Unfortunately, yes. Alice isn't crossplatform, is it? No, it's based on Direct3D retained mode (version 3, no less) and will not be portable until and unless that changes. > But what does any other IDE have what Idle does not have? Idle is > crossplatform, isn't it? As of a few weeks ago, at least, it did not run on the Macintosh. As much as I dislike MacOS, the Macintosh is important in many educational settings. I'm not clear on WHY it does not work on the Mac. Dave Scherer

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Re: [Edu-sig] Age groups
by Steve Morris Feb. 4, 2000

Feb. 4, 2000

Gerrit Holl writes: > Ivan Van Laningham wrote on 949667945: > > Guido van Rossum wrote: > > > Steve Morris wrote: > > > > That's funny. My experience was quite different. When I first saw > > > > objects and classes it was like a relevation from God. They seemed > > > > intuitively obvious and the answer to my prayers. I wonder if this is > > > > a right brain/left brain thing or something. > > > > > > Gerrit is definitely a left-brain type of person :-) > > > > We ought to make up posters advertizing Python, and put Gerrit's picture > > on them. > > Sorry, I don't understand you both. Am I left-brain? > What does left-brain has to do with object oriented design? I can't speak for Guido and Ivan's follow ups but as the author of the original reply to your post I was pondering why some people find objects a difficult subject and others find them obvious and intuitive. That's quite a dicotomy. There doesn't seem to be anyone in the middle on this subject. It is clearly not an issue of programming ability because senior experienced programmers come down on both sides. Since left brain and right brain people are often categorized by their different problem solving strategies I was wondering out loud if this particular problem solving technique (OOP) exemplified some of those differences. If you are interested in this subject and determining which category you fall in you can probably find many references on the WWW. Actually left/right brain has been replaced with a more sophisticated breakdown defined by the Myers Briggs profile. Left/right brain turned out to be a little too simplistic to be generally useful. A quick synopsis is that left brain people are described as rational and pedantic with right brained people being intuitive and artistic. As I said... a major simplification. I find the suggestion interesting that experienced programmers often have more difficulties with objects than beginners. That isn't my personal experience but I have heard it said many times. BTW this topic may seem a little off point except that we need to teach people with different learning strategies. There is a tendancy of programmer types to use left brain teaching techniques and thus lose half their audience out of the gate. Anyone who has ever sat in front of a room full of young students knows that there are as many learning strategies as there are students. CP4E needs to be sensitive to this or it will be one more also ran strategy.

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baby steps, packaged
by Hank Fay Feb. 4, 2000

Feb. 4, 2000

Hi all, my connection with education is as a psychologist for 25 years, and a developers consultant for a couple of years (with 20 years of programming thrown in on the side -- no, I'm not 85 <s>). In addition, a good friend is heading a startup that packages educational software for classroom use. I also grew up in education: my father was a teacher/guidance counselor/high school principal, and my older sister a teacher for 30 years. Making things practical, and packaged, is the key to getting them in the classroom. Give a teacher a program that meets the level of her students, and a lesson plan that goes with the software, together with a teaching guide, and if it works, it will be adopted. Give them building blocks they have to put together themselves, and adoption will be spotty. Tying the software/lesson plans into national curriculum standards would be real plus: this is work that the teacher doesn't have to reinvent. What standards? What does developing software entail? What doesn't it entail? <s> Wouldn't it be great for writing courses to teach documentation skills? (Speaking of which, check out the "fast and easy" series of teaching books for MS products -- they are written, or rather not written, in a style which speaks to the average person.) Psychologist Jerome Bruner maintains that all complex concepts are isomorphs of simpler concepts; same shape, different levels of complexity within. I think that has to be the organizing principle for the K-12 curriculum, or whatever range is chosen. Now, our range of convenience (a term from George Kelly's Personal Construct Theory, important in this task because we have to realize our limitations in seeing things the way little people see them) is in standard programming, so I would start there, and then work backwards. Describe the end tasks of the multi-year curriculum first. Then work backwards. You will need educational specialists at the different age levels to tell you the level of cognitive complexity appropriate to an age group. Thus my $.02. Hank Fay http://www.prosysplus.com

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Re: [Edu-sig] On case sensitivity
by David Scherer Feb. 4, 2000

Feb. 4, 2000

-----Original Message----- From: David Scherer [mailto:dscherer@cmu.edu] Sent: Friday, February 04, 2000 1:09 PM To: Jim Harrison Subject: RE: [Edu-sig] On case sensitivity > Though I have no objective evidence to show, I would guess that one of the > main problems with case stems from Python's ability to create variables > on-the-fly (without declarations). If variables are required to > be declared > up front, most case errors involving variable names would be caught > immediately as syntax errors and fixed. In Python, a case error in an > assignment statement would create a new variable with a new name. > This would > yield a logical error with unpredictable results that might be very > difficult for a beginner to track down. I can imagine a novice staring at > the code for a long time without seeing the problem in a situation like > this. One such episode, and I'd tell my teacher that the main problem with > Python is case sensitivity. Variable declarations also add a lot of cognitive overhead - one more meaningless piece of syntax that would be a prerequisite to _doing something_. As I pointed out earlier in the thread, the typo problem is not limited to case errors. I think it should be addressed by checking the user program for identifiers that are used as lvalues and that appear exactly once in the program. That addresses both case errors of the type you describe and other typos. > It would be interesting to see whether the case errors that make an > impression on beginners are the ones that yield immediately > identifiable and > fixable syntax errors, or the ones that yield logical errors. In the case of the Alice trials, almost certainly the immediately identifiable errors! Alice code usually looks something like: DoInOrder( bunny.Move(UP,3), bunny.Turn(LEFT,1/4), bunny.Move(DOWN,3) ) Since there are rarely any assignments at all at the level of the tutorial, logical errors are unlikely. However, beginners who do not understand the difference between the different kinds of constructs in this program (functions, methods, constants, objects) don't understand why all of the identifiers have different required case. > That being said, I vote for Guido's approach of handling this in > the IDE as an optional feature. Agreed, but it must be useful when enabled! It's easy to accept any problem with something by saying "oh, well you can always turn it off." Dave Scherer

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Re: [Edu-sig] Learning/Teaching Python
by Dirk-Ulrich Heise Feb. 4, 2000

Feb. 4, 2000

-----Ursprüngliche Nachricht----- Von: Elizabeth Byers <ebyers(a)mountain.org> An: edu-sig(a)python.org <edu-sig(a)python.org> Datum: Freitag, 4. Februar 2000 16:11 Betreff: [Edu-sig] Learning/Teaching Python [...] >I know it will be an uphill battle to >convince teachers that it is worth the effort to try this, >instead of just teaching word processing and MS Office. Being german, i know nothing about the american schools; but is that really true? They teach something like Winword in school and omit programming? Okay, maybe this sort of stuff happens today in Germany as well, it's a while ago that i left school. I remember sitting in front of CBM 4032 (yeah okay, it's AGES since i left school...) machines and learning to program them in BASIC. The math teachers ran the courses voluntarily and they always wanted to convince us that Pascal is better. (This wasn't true for several reasons: Pascal had a slow compiler, BASIC was interpreted immediately; Pascal had a impractical type system (no casts), BASIC had nearly no types (no types == no errors). But the worst thing was: Pascal didn't allow to poke bytes into memory, so we needed BASIC to get our machine programs running, for really fast graphics. That was when the math teachers realized they had lost control. Anyway. ) Hmm. You could show them how a Python takes control over Word using the COM interface. This would show them that Python is mightier than Word. (The snake is mightier than the feather.) Dirk

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