I filed the following quick comment after viewing a six minute tutorial on variables and values at ShowMeDo.
The video: http://showmedo.com/videotutorials/video?name=6950010&fromSeriesID=695 My comment: """ idea that values are "stored into" a variable is less the metaphor in Python, which is more about assigning or binding names to objects with the assignment operator (=). The problem with "store into" is then its hard to picture many names for the same object, yet that's easy when you think of a balloon with many strings. """ Yikes it posted three times dammit, makes me the foolish dweeb. Anyway, based on our longish threads here awhile back, I think "we who consider ourselves Python teachers" should actively check ourselves against using the verbs "to store in" or "store into" with respect to objects and their top-level names. The reason is, once you picture a dog in a doghouse, with the variable name as the doghouse, then it's hard to visualize how other doghouses could contain the same dog (the same value) without there being multiple copies of the same dog (clones?). A better image is balloons on strings. I realize it's not customary to have one helium balloon with two or more strings, different hands holding each string, sharing the same balloon, but there's nothing conceptually difficult about it (feels kind of ubuntu), whereas with that dog in the doghouse... that way madness lies. As several teaching professionals were noting on this list, a Python name is a lot more like a C pointer in the sense that it neither grows nor shrinks with respect to that which it names, i.e. the "size of object" is not a name's concern (another way to break the hold of the container-contained imagery). I think when we teach low level (including but not limited to children), we actually mess with (rewire) basic associations, a common technique in pedagogy (called "mnemonics"). For example, the so-called "equal sign" (=) would be better called an "assignment operator" as most of us here do. To make this link stick we could explain how the two parallel lines represent "opening a channel to" i.e. now this name (on the left) will be able to communicate with the object on the right (some result of evaluation). Why "open a channel to"? Because now we have "dot notation" i.e. our little API "control panel" at the near end of the string, our little "interface words" (triggers, attributes, methods with args)... our "messages" (to use Smalltalky talk). We don't really want s = 3 to be read "s equals 3" in Python. It's closer to "s names 3" or "s represents 3" or even "s speaks for 3". Not "s stores 3", nor "s contains 3". Probably the idea of "garbage collection" should be introduced right at this juncture, with arched eyebrows ala Spock if we forget to mention it. That's a really good way to anchor the many-to-one strings-to-balloon metaphor, with the idea of a reference counter on the object. Dogs in doghouses don't have reference counters, plus we wouldn't want them garbage collected. Balloons, on the other hand, go pop, which'd be a convenient way to represent "freeing up memory". Kirby PS: do Python's where Prada? http://fashionshops.wordpress.com/2009/05/18/prada-ad-campaign-ss-2009/ _______________________________________________ Edu-sig mailing list Edu-sig@python.org http://mail.python.org/mailman/listinfo/edu-sig
