O.W.L.s and how they're calculated

[Ali]

No: HPFGUIDX 89825


I, Ali wrote:

>>> Whenever I have read OoP, I have always assumed that the DADA is 
 made up of two parts, the written exam and the practical exam. 
 However, Galadriel Waters states that the 
 
 "Written exam for a class is worth one OWL;and the pratical exam 
 is worth one OWL; so, each subject is worth two OWLS" p. 109. 

 Now, it is possible that this is how they're calculated, but it 
 seems unlikely.

 
 The subjects I've multiplied are the subjects which seem to have 2  
separate parts. That would mean Harry could theoretically achieve 
> 15  O.W.L.s, 3 more than both Bill and Barty Crouch Junior.>>>
 
 Meri responded:

 <<<I always thought that you got you got one OWL for each 
 passing grade and that some subjects had two exams, a written exam 
 and a practical exam where applicable. For example: 
 Divination - practical exam (reading tea leaves, etc.)
 DADA - written and practical (theory and actual defense techniques)
 Charms - written and practical 
 Transfiguration - written and practical 
 CoMC - written and practical
 History of Magic - written exam (essay questions)
 Muggle Studies - written exam
 Runes - written exam
 Arithmancy - written exam 
 Astrononomy - practical and written exam would be almost the same 
 here
 Potions - written and practical 
 Herbology - practical 
 By my count, I get sixteen OWLs, and 12 of 16 would be very 
 acceptable. Harry could potentially get 13, and, if that is the 
> normal schedule of exams and classes, then 12 for 13 is excellent. 
>>>

Ali again,

Erm, I've used your way of counting from your list, and I still 
reach 18, with Harry being able to do 15.

I'm not saying that this is necessarily wrong, but I am saying I 
think it's unlikely and that I'm not aware of any evidence for this. 
If each separate exam was worth an individual O.W.L.,then it would 
mean that some subjects would count double compared to others. 
Admittedly, it tends to be the compulsory subjects which have the 
practical paper and therefore you could argue that this has been 
designed to weight the subjects according to their importance, but 
again, there is no evidence to support this. I still believe that 
the written and the practical exam contribute to the final O.W.L. 
grade for each subject, and Waters did dress up an assumption as a 
fact.

Ali