[HPforGrownups] Impossible timetable

[Betty]

No: HPFGUIDX 38384

I'm starting to write a fanfic and I needed a more comprehensive look 
on the school timetables. So I took PoA and started to analize it 
looking for answers... and unless I'm very mistaken, it turns out 
that either all teachers (or most of them) use timeturners, or there 
are more teachers than canon states, or JKR simply failed to see an 
impossible schedule. 

Usually, the kids have 2 classes during the morning, then Lunch, then 
another class (perhaps 2?). After thorough reading, I could come with 
the following:

First day of classes: 
- Divination/Arithmancy/Muggle Studies (apparently with Hufflepuff, 
as Ernie MacMillan tells Ron Hermione hasn't missed a class) 
-  Transfiguration
=lunch=
- Care of Magical Creatures (with Slytherin)

Now maybe some british members can bring some light here: Is 
September 1st the first day of school in britain whatever day of the 
week it falls into? Sept 1st was wednesday in 1993 when  PoA takes 
place - So if students took the Hogwarts express that day, the first 
day of school would have been thursday, Sept. 2. Yet we know they 
have Potions on thursday (PoA7), so it's more likely they got to 
Hogwarts on Aug. 31 thus starting lessons on Sept 1st. 

Thursday schedule:
- Potions (with Slytherin)
=lunch=
- DADA

Yet in PoA9 Snape asks the werewolf essay "for monday morning" 
suggesting (and supported by PoA10) than Monday's schedule is the 
same as Thursday. Hence it has no sense Snape's request for "monday 
morning" since they complain about it to Lupin on monday afternoon! 
And since he says they need not to write the essay, it's obvious 
Snape didn't ask them to surrender it Potions.
>From PoA15 we can deduce:

Tuesday? or Friday? schedule:
- Arithmancy / CoMC
- Charms
=lunch=
-Divination

We don't know when History of magic, Ancient Runes and Herbology are 
placed in the timetable (I don't count Astronomy bc we know it's 
lectured late at night). We know they have Transfiguration after 
Herbology (PoA8). It is mentioned nowhere whether or not do they have 
any class after the first afternoon class, though it seems they 
haven't. (And naturally I can speak only for the Gryffindors).This 
would give us a hourly load (gee I don't even know if there is a word 
in english for that, I hope you understand what I mean) per week as 
follows:

Potions: 4
DADA: 2
Divination: 2
CoMC: 2
Arithmancy: 2
Charms: 1 
Transfiguration: 1
Muggle Studies: 1
Herbology: 1 or 2 (it's double in CoS and GoF, but in PoA8 
Transfiguration comes right after it so it can't be double)
History of Magic: unknown
Ancient Runes: unknown
Massive snipping:
Nuri
It's not unlikely, though, that all comes down to JKR's mistaking the 
days of the week. For example, When Lavender cries for her dead bunny 
between classes, the 16th of october...it was saturday in 1993! (PoA8)
*I don't think JKR used a calendar.  It seems to be a different time
frame altogether.  The full moon apparently wasn't on June 6 in '93,
either.  So it's not a mistake; she's arranging it how she wants it...I
suppose.
Betty