I was just thinking along these lines again when I read the July 2 update.

Chapter 15:

"You needn't apologize, Mr. Potter, if you were required to read ahead you would have been told to do so." McGonagall's fingers rapped the desk in front of her. "Mr. Potter, would you care to guess whether this is a desk which I briefly Transfigured into a pig, or if it began as a pig and I briefly removed the Transfiguration? If you had read the first chapter of your textbook, you would know."

Harry's eyebrows furrowed slightly. "I'd guess it'd be easier to start with a pig, since if it started as a desk, it might not know how to stand up."

Professor McGonagall shook her head. "No fault to you, Mr. Potter, but the correct answer is that in Transfiguration class you do not care to guess. Wrong answers will be graded with extreme severity, questions left blank will be graded with great leniency. You must learn to know what you do not know. If I ask you any question, no matter how obvious or basic, and you answer 'I'm not sure', I will not hold it against you and anyone who laughs will lose House points. Can you tell me why this rule exists, Mr. Potter?"

Because a single error in Transfiguration can be incredibly dangerous. "No."

"Correct. Transfiguration is more dangerous than Apparition, which is not taught until your sixth year. Unfortunately, Transfiguration must be learned and practiced at a young age in order to maximize your adult ability. So this is a dangerous subject, and you should be quite scared of making any mistakes, because none of my students have ever been permanently injured and I will be extremely put out if you are the first class to spoil my record."

Chapter 26:

"Professor Quirrell," said Harry gravely, "all the Muggle-raised students in Hogwarts need a safety lecture in which they are told the things so ridiculously obvious that no wizardborn would ever think to mention them. Don't cast curses if you don't know what they do, if you discover something dangerous don't tell the world about it, don't brew high-level potions without supervision in a bathroom, the reason why there are underage magic laws, all the basics."

Chapter 28:

Earlier, Harry had very secretly - he hadn't even told Hermione - tried to Transfigure nanotechnology a la Eric Drexler. (He'd tried to produce a desktop nanofactory, of course, not tiny self-replicating assemblers, Harry wasn't insane.) It would have been godhood in a single shot if it'd worked.