History has a Plan!
Professor Binns was disappointed.
This was not a new state of affairs for him. Unfortunately, that only compounded the problem, for it meant he was bored as well.
At least boredom was a general problem of everyone in the class, so that was some consolation.
Professor Binns knew he was boring. He had spent his entire life (and afterlife) perfecting his boring techniques. He was reasonably sure he could put a class under in about five minutes. It was really an unappreciated skill - people didn't realize how much effort it took to find the learning material, present in the most boring way possible (which was hard with the material so interesting), and have the perfect droning tone and cadence (even harder without a voice-box).
You may ask, then, why did Professor Binns continue teaching when he knew he was not teaching anything more than how to go to sleep?
Because it was all part of The Plan.
Yes, The Plan. An enormous conspiracy, stretching back to when Bernard Binns was young and idealistic, and not yet a professor. At the time, he had been a fierce advocate of goblin rights. However, he and his goblin allies soon realized that using the normal channels would never gain them the independence they craved. They considered rebellion and war, but wizards, even if they divided, were too strong, and the previous goblin rebellions had merely managed to bring things to a stalemate.
So they made up The Plan. Only goblins (with a few wizards mixed in), could have thought up such an elegant, long-term plan. It was quite simple, actually: lull the wizards into a false sense of security, and wait. Eventually, they would have some crisis - Civil War, Plague, Famine, etc. Immediately after it ended, the goblins would strike.
To do so, the Goblins became settled. They became respectable bankers, money lenders rather than warriors. it was a front, of course, but it also had a purpose - 'He who has his thumb on the purse has the power'. Nonetheless, they kept up the secret training of warriors.
However, all this was worthless if the wizards still remembered what the Goblins were capable of. So Bernard Binns became Professor Binns, and went on to teach History of Magic in Hogwarts, doing so in such a manner that either nobody would know it, or they would only know it by rote, but not understand it.
After all, 'Those who cannot remember the past are condemned to repeat it'. And 'A people who do not know their past, their present is poor and their future is lost in a haze'.
Of course, they had to give the wizards a chance. There was a reason why Professor Binns' lessons nearly always centered on the Goblin Rebellions. A clever student could notice some discrepancies and hints, and realize the troubles that were brewing under their noses.
Usually, however, these clever students were also clever enough to realize the Wizarding World would never believe them, and found themselves joining the goblins.
This is a Social Experiment
Sybill Trelawney puttered about in her tower, making a cup of tea.
She was feeling quite joyful today. And it wasn't even the sherry. It was the success of another one of her games.
Most people did not know or were not aware, but Sybill Trelawney had been a Ravenclaw, though the Sorting Hat had offered her Slytherin.
It seemed absurd. How could such an obvious fraud be a Ravenclaw? Yet she was the Professor of a subject which was impossible to learn, even more impossible to teach.
It all started when Sybill was sixteen, and had given her first true prophecy. Until then, she had given vague and self-fulfilling prophecies, playing off the fact her grandmother had been a celebrated Seer and doing it for fun. But when she gave her first true prophecy (regarding a break-up of the steadiest couple in Hogwarts), she suddenly realized the power she wielded. Within a fortnight, the couple had broken up. She couldn't understand. She had never believed in destiny or fate. And yet people were such sheep that because a teenager had entered a trance and uttered some words, they left the person who was dearest to them.
It became her new interest. She read Oedipus Rex and other books of prophetic stories. It became obvious that people would do anything if they knew it was because a prophecy said so. Sybill had always been a people person - in the sense that she enjoyed finding out what made them do things. She realized that when if she continued to make prophecies, she would have an endless stream of social experiments, which was exactly what she wanted.
She soon realized that in order to keep it a real experiment and protect herself it was best to spout vague or self-fulfilling prophecies most of the time, and pretend not to remember her true prophecies. Having quickly gained somewhat of a reputation, she used it in order to gain the position of Divination Professor. It gave her so many more opportunities to test her social theories. So she spouted nonsense, made vague prophecies (some of which she fulfilled herself - sending that Gryffindor girl's rabbit a poisoned carrot was too easy), and watched her students to see which ones had figured it out.
That was why she liked Harry and Ron so much. They had begun to understand her game, and were trying to play it. Of course, they didn't know the rules yet (they thought she centered on death, when in truth, it was completely random), but they still had a few years in which they could learn... and there would be others after them.