[Year 12 IPM] Exam Post Mortem now online

[Mark Kelly]

Mike Brookes wrote:
> Hi Mark et Al
> Thank you Mark for providing the starting point for the carping, 
> bickering and protesting.
> First an agree whole heartedly (always start on a positive note :-))
> 
> Q6b) I agree that an IPO chart is about Input (data), Processing (might 
> be called tasks but steps would be better) and Output (details of what 
> information is produced) and that the I and O in IPO diagrams refer to 
> items not tasks.
> 
> Carping:
> Q3) The method used to store data on a DVD RW is not pits in an 
> Aluminium substrate - that's the method used to store data on mass 
> produced Cds and DVDs that are read only.
> 
> DVD RW disks use a polycrystalline layer (usually an alloy of Silver, 
> Indium, Antimony and Tellurium). In the normal ordered crystalline state 
> the layer is shiny and reflects a low powered laser.

You know - I was JUST ABOUT to say the very same thing but I didn't know 
what I would be talking about.

I *was* wondering how burnt pits could be erased and rewritten.  I put 
that in my 'List Of Things To Check Out'.

It did concern me what my kids would say for that answer...

> When the alloy is hit with a short high power laser burst the alloy 
> melts (500 -700 degrees) then cools down quickly so that it forms an 
> irregular mass of tiny crystals rather than the ordered crystalline 
> form. This irregular form has a low reflectivity and scatters the low 
> powered laser used to read the disk.
> 
> To erase the data the laser is used at medium power to heat the alloy to 
> above the re-crystallisation temperature but below the melting point 
> (around 200 degrees) for a sufficient time to allow the alloy to 
> crystallise back into its shiny form.
> 

Many thanks for that. I really must brush up on my CD/DVD burning 
knowledge.  I have a hazy understanding at best. The problem is that by 
the time I understand it, it will have become quaint historical folklore...

> Once upon a time in a galaxy far, far away IPM was a subsection of 
> Information TECHNOLOGY - 'tis great to see a question which actually 
> requires the students to know a bit about technology instead of being a 
> glorified business management course. :-P

Grrr!  Yes!  We seem to be something of a BusMan elective! I gripe about 
this in one of my responses (Q12?)

> PS difficult to see how the question could be interpreted as how would 
> the end user store data on these devices as you would use the same 
> answer for all three - eg. drag the file icon to the icon representing 
> the device/directory.

Yeah.  Agree.

> Bickering:
> Q9 - Disagree that its only a systems question - Validation is a major 
> part of an IPM solution so it is fitting that the validation should be 
> tested and that appropriate data be selected to do the testing.

Agree, but defining test data is a bit more than IPM students are 
normally expected to work on.  When I explain "test data", "boundary 
conditions" etc, I am usually greeted by facial expressions reminiscent 
of the last scene of 'One Flew Over the Cuckoo's Nest'

(If that means nothing to you, consider this a great opportunity to ask 
an English/Media teacher a mind-expanding question!)

> 
> Protesting
> Q5 Eneey Meeny Miney Mo section
> Not a dogs breakfast - offered it to dog and said mutt ran off howling. 
> RSPCA investigating :-)

Woof!  I dare VCAA to claim ANY valid answer for that one!  I'd be proud 
if the offical examiner's report said:

"This question was excised from assessment.  Any answer earns 1 mark. 
Any abusive, violent, handwritten commentary in the margin earns 2 
marks.  Correct spelling of 'incompetent' or 'ignorant' earns a bonus mark."

> 
> Mike Brookes
> Chief cook and bottlewasher

LUXURY!  You only 'ave to wash the bottles?  I 'ave to MAKE 'em meself!

> Copperfield College
> 
> Mark Kelly wrote:
> 
>> My annual whinge is now online at
>>
>> http://www.mckinnonsc.vic.edu.au/la/it/ipmnotes/exam/2005exam/index.htm
>>
>> Feel free to carp, bicker and protest.


-- 
Mark Kelly
McKinnon Secondary College
IPM Lecture notes: http://vceit.com
Moderator: IPM Mailing List