Muggles' Guide to Harry Potter/Major Events/OWL exams

Overview
The OWL (Ordinary Wizarding Level) exams are taken at the end of a student's fifth year at Hogwarts.

OWLs are offered in most subjects a student takes in their first five years, and many consist of both written (theory) and practical tests. Courses in which OWLS are offered are Ancient Runes, Arithmancy, History of Magic, Muggle Studies, all of which have written sections only; Astronomy, Care of Magical Creatures, Charms, Defence Against the Dark Arts, Herbology, Potions, Transfiguration, all of which have theory and practical exams; and Divination, which seems to have only a Practical section. Thus for twelve available subjects, nineteen examination slots are required.

Event Details
Apparently, OWLs extend over two weeks, with exams morning and afternoon; generally theory in the morning, practice in the afternoon. Special anti-cheating quills and parchment are used for the written parts of the exam. In Harry's fifth year, when he takes OWLs, Harry sits Charms on the first day, then Transfiguration, Herbology, and Defence Against the Dark Arts. On the Friday, Hermione sits Ancient Runes, while Harry and Ron have the day off. The following week is Potions on Monday, then Care of Magical Creatures on Tuesday. Wednesday we see Astronomy theory in the morning, Divination in the afternoon, then the Astronomy practical exam was that night at midnight. Thursday afternoon was the History of Magic exam. Hermione also had to sit her Arithmancy exam Wednesday afternoon, when Harry and Ron had Divination. None of the Trio are taking Muggle Studies, so we do not know when that exam occurs; but as it, like Divination, Ancient Runes, and History of Magic, likely only has a theory part, the exam could take place on the Thursday afternoon, following History of Magic, or on the Friday following Ancient Runes.

OWLs are graded using the following system:

Passing Grades
 * O - Outstanding
 * E - Exceeds Expectations
 * A - Acceptable

Failing Grades
 * P - Poor
 * D - Dreadful
 * T - Troll

The examiners are not Hogwarts professors, but a group of independent examiners referred to as Wizarding Examinations Authority, apparently somehow under the aegis of the Ministry of Magic. They are described as “a small group of ancient-looking witches and wizards”.

In the first few classes at the start of the term, a number of teachers announce that they will be grading to OWL standards. Harry, Ron, and Hermione discuss between themselves what OWL standards mean. In their discussion, they are joined by Fred and George, who sat their OWLs two years earlier. It is the Twins who describe the various grade levels, saying that they should have received E in every course, as their just showing up for the exam had exceeded the expectations of the Hogwarts teachers.

In the same book, Harry, viewing one of Professor Snape's memories, sees the Marauders (Sirius Black, Remus Lupin, Peter Pettigrew, and his own father) at the end of their Defence Against the Dark Arts OWL.

Notable Consequences
The grades achieved in O.W.L.s are very important for the next stages of a young wizard or witch's education. Each teacher demands a minimum grade for further study of his or her subject at NEWT level. Most teachers seem to demand at least an E, while some demand an O and others allow students with an A, the lowest passing grade, to proceed. In particular, Professor Snape requires that students who wish to proceed to N.E.W.T.-level study of Potions must achieve an 'Outstanding', while Professor McGonagall and Professor Flitwick require at least an 'Exceeds Expectations' or higher.

As the results of the OWL exams determine which courses can be taken at the N.E.W.T. level, the O.W.L. exams affect the witch or wizard's career choices. It is for this reason that Harry's meeting with Professor McGonagall concerning choice of careers occurs before the O.W.L. exams. In particular, Harry, asked to consider a career, is most intrigued by the idea of being an Auror, a career for which he must achieve N.E.W.T. grades of at least an 'Exceeds Expectations' in at least five subjects. Professor McGonagall suggests Harry's subjects should include Defence Against the Dark Arts, Transfiguration, Potions, and Charms.

When Harry receives his results, he discovers that he has passed everything, except Divination and History of Magic. He has achieved a 'Poor' in Divination as it is his weakest subject and a 'Dreadful' in History of Magic since he fainted mid-way during the examination, rendering him unable to finish his paper. While Harry does achieve an 'Acceptable' in Astronomy and an 'Exceeds Expectations' each in Transfiguration, Charms, Potions, Herbology, and Care of Magical Creatures, as well as an 'Outstanding' in Defence Against the Dark Arts, Professor Snape's requirement that he achieve an 'Outstanding' for NEWT-level Potions studies seems to prevent his becoming an Auror. However, Harry still manages to get into N.E.W.T.-level Potions since Professor Slughorn allows post-O.W.L. Potions students to continue to N.E.W.T.-level with at least an 'Exceeds Expectations'.

It is while Harry, tired after endlessly re-hashing the arrest of Hagrid that had occurred during the Astronomy final, is trying to complete his History of Magic exam that he faints and has the dream of Sirius being tortured in the Ministry by Voldemort. Through this dream, Harry goes to the Ministry.

Analysis
The fact that the Wizarding world has an equivalent to the English GCSE is only to be expected; its sharing a name, largely, with the older O-level exams is likely an artifact of the author's age. The standardized testing in the Muggle world that so pervades the school system must have a parallel. The stress and fatigue surrounding the GCSEs no doubt has made many young Muggles imagine things that just are not so. Similarly, the mental tension and exhaustion caused in Harry by these exams obviously will increase Harry's sensitivity to the images that Voldemort is sending to lure Harry to the Ministry. Given that we have seen earlier that Harry is able to pick up mental impressions at times Voldemort is experiencing extreme emotions, it is safe to speculate that the author arranged events to heighten Harry's tension in this book, culminating with the critically-important OWL exams, specifically to make the transfer of thoughts more likely.

Questions

 * 1) Is Troll a real exam grade? Why did the Weasley twins have trouble remembering it?

Greater Picture
It is mentioned that Harry believes his hopes of becoming an Auror to be futile, when he receives his OWL grades at the beginning of Harry Potter and the Half-Blood Prince. In fact, this is not quite true; the requirement is that Harry achieve Exceeds Expectations in at least five NEWTs, and he has received five Exceeds Expectations and one Outstanding at OWL level. It appears that he would be able to proceed in five NEWT-level courses even if Snape was still teaching Potions and would not accept him in that course; that he take Potions at NEWT level was a recommendation by Professor McGonagall, rather than a requirement. Once he arrives at Hogwarts, he will find that a new Potions instructor has been appointed. Professor Slughorn will accept an OWL grade of Exceeds Expectations for NEWT-level studies, so Harry's hopes of becoming an Auror will be restored.

Harry's belief that Professor Slughorn has been brought in to be the Defence Against the Dark Arts teacher, and his associated belief that he will not be allowed to study NEWT-level Potions, is a necessary plot point. It is because of this that Harry does not purchase the necessary textbook for NEWT-level potions, instead receiving the textbook previously owned by the Half-Blood Prince. This textbook is instrumental in Harry's success in Potions in his sixth year, and teaches him spells that he will use during the rest of the story.