Ginny tiredly pushed her way into the Hogwarts Great Hall, on the first day of class, the enormous room lit up with the fresh ambiance of the morning. The room was already lively and the air was filled with conversation. She blinked slightly, still exhausted - she had wondered endlessly yesterday about the contents of the mysterious letter Harry had been given at the Feast. Students usually only received their mail once a day at Hogwarts, and owls were never allowed to enter the Hall any other time of the day.

Luckily her first lesson would be Rationality, so she would be able to find out about the letter. Most first years would probably have preferred a lesson where they could finally start learning magic, but Ginny was happy enough to wait until the second period, when they had their first Defence Against the Dark Arts lesson. She walked to the Slytherin table and sat down next to another first year girl. She tried to start a conversation with her but her attempt was met with rejection. The girl did not seem to be in a good mood, which astonished Ginny. She thought that all students would be exited on their first day of Hogwarts. Besides the first year girl, Ginny was surrounded by a group of people who Ginny estimated to be in their third or fourth year. The seemed to be close friends so Ginny did not try to join their conversation. After eating in silence for a while, she heard the fluttering of wings behind her. She looked upwards and saw dozens of owls flying through the Hall and dropping packages left and right. As a wizard-born she was used to getting her mail delivered by owl, but the picture of all the different looking owls in the sky was still beautiful. The Girl next to her however was clearly not used to the Wizarding postal system. Her jaw had dropped and a very confused expression crossed her face.

"Wizards usually get their post by owl," explained Ginny, thinking that this migh be a chance to get into a conversation with the Girl, but a moment later, something dropped out of the sky and landed on Ginny's plate. It was a copy of the Daily Prophet, more precisely an ancient-looking owl carrying a copy of the Daily Prophet, which she found somewhat confusing. Her parents subscribed to the Daily Prophet, but could not afford more than one copy and in Hogwarts, news spread quickly, so it wasn't necessary to have your own copy.

She looked at the paper and saw that it had already been used. Her parents must have read it already and then sent it to her. It explained why Errol looked so exhausted, he whizzed through the air at top-speed to be here in time for the Hogwarts mail delivery. Something important must have happened that her parents did not want her to hear from second hand news. She would share the Prophet with her brothers later on. It probably only went to her, because the Slytherin table was closer to where Errol had entered the great Hall than the Gryffindor table. She pulled out the newspaper from under the owl and read the headlines.

"AZKABAN ATTACKED"

"DEMENTORS NOWHERE TO BE FOUND"

"NO PRISONERS MISSING"

Her first thought was 'what?'. Naturally following this, her second thought was that it must have been Harry. After all, rumours were that he had frightened a Dementor last year without even using a Patronus Charm. But why would he do that? The prisoners in Azkaban were evil, and now it would be a lot harder to stop them from escaping. Before she could think further about this, the door of the Great Hall suddenly burst open with an enormous strength. She looked at the door and saw a small girl entering the hall, walking towards the Ravenclaw table.

A bit out of breath Ginny entered the Rationality classroom. She had spent quite some time after Breakfast Discussing the Azkaban breakout with the other Slytherin first years, so she went off from the Great Hall later than she had planned. Fortunately Hogwarts had done nothing to sabotage her on the way to class so Harry was not yet there when she arrived. She sat down next to a skinny blonde boy with blue eyes. Because there was still some time left she decidet to start a conversation and said: "Hi, I'm Ginny. You were at the Sorting yesterday...you're Dudley, right?"

"Yeah," answered Dudley. He looked at her for a while, as if he wanted to say something else and then turned back to his food.

"You're a Muggleborn right? At least I don't know any wizarding family named Dursley. How do you like Hogwarts so far? Are you excited to finally learn magic?"

"Seems to be better than at home. And I sure am excited about learning to use magic."

"Not a very talkative guy, are you?"

"I'm not really used to talking to people. I didn't have many people to talk to."

Ginny considered, just then, asking him why, but decided not to question Dudley about his Muggle life for now. Perhaps it would be better not to prod around too much with what were clearly unhappy memories for him. "Well," she said, "I'm sure that's going to change now that you're in Hogwarts - but if you want people to talk to you, you should work on your communication skills. Right now it's hard to keep a conversation going with you, because all you do is answer questions."

"So what else should I do?"

"Maybe you should ask a question yourself. Right now I already know quite a bit about you, but you know nothing about me."

"Mhhm, okay. Are you Wizard born?"

"Yes, I come from quite an old pure blood Wizard family. Not that I think blood purity is important, like some other old families do."

"Why do they think it is important?"

"They think that pure-blood wizards are stronger and that the magic gets weaker if you marry Muggleborns. There is some evidence for that theory since lots of wizards of the old houses are quite strong, but there are also very strong Muggleborns. Hermione Granger is also Muggleborn and I heard that she is the strongest witch in the year above us. And one of the two most powerful wizards of our century was no pureblood as well."

"Who was he?" asked Dudley, but before she could answer a door opened and Harry entered the room. He took a few steps into the room and then said "Hello everyone, I'm Harry Potter - you can call me Professor," He smiled and then continued. "To be honest, I've wanted to do this since I was six, but I expected to have to wait until I was at least 18 to do it - and I certainly wasn't anticipating teaching at a school for magic. Anyway, my compliments to all of you on making the decision to attend this class. I congratulate you on that - but be honest - did any of you actually think the decision through properly? Maybe you just felt it would be a good thing to do and went through with that feeling. Well in this case your feeling was right, but in this class I'll show you how to judge whether your feelings are right and whether to follow through with them. In this class you will learn how to make better decisions. So before I begin, does anyone have an idea on how to make good decisions?" he looked around at the not-entirely-silent hall before a hand shot up.

Miss Weasley, you have a proposal?"

"Well you have to think if the result of the decision will benefit you. If you take this course, as an example, you would have to ask yourself if the content of this course will be helpful."

Harry nodded approvingly. "Indeed, looking at the expected benefit of an action is something you should do. However not everything that gives you a benefit is good. If I would allow you to choose between getting a Sickle and a Galleon from me, both choices would give you a benefit, but the galleon would be significantly better. So when considering options, don't just think 'that's good,' but compare it to the alternatives! They might be better." He cleared his throat before continuing.

"This concept, called 'opportunity cost,' means you need to ask yourself the question 'good compared to what?' Well, a Sickle is certainly good, but 'good compared to a Galleon?' Now the Sickle isn't a good choice. Of course, you don't always get a decision that's so clear-cut. Even if uncertainty isn't involved. In this example it's easy to know that a galleon is worth more than a sickle, but if you have to choose between other things than just money is harder to decide which one actually gives you more utility. I'll show you right now."

Harry took out his pouch and started to pull out various sorts of sweets, some Sickles and Knuts, and lots of other things like books, potion ingredients and things from Zonko's Joke Shop. He muttered a spell and things started to fly through the classroom.

Murmuring started, some people reached out their hands. "Don't touch anything before I say so, believe me you will regret it." Harry said sharply. "You will have the chance to acquire some of these wonderful things, but not all of them. You will be able to choose, between two groups of items several times. You will get the things you choose and you won't have to give them back after class, so choose wisely. I want you to write down why you preferred the things you took over the others. You can start now, all you have to do is say if you want the left or the right pile."

In front of Ginny lay two chocolate frogs on the one side and ten sickles on the other side.

For an instant Ginny thought about taking the sweets since chocolate frogs where one of her favourites, but then she realised, that she could buy way more than two chocolate frogs with 10 sickles.

"Right pile," she said, and an instant later the frogs vanished. It was a bit cruel to see your favourite sweets vanish before you and she decided to buy herself at least three chocolate frogs with the money she just got. Her next choice was between three boxes of Bertie Bott's Every Flavour Beans and some Acid Pops on one side and 5 sickles on the other side. This time the sweets were worth more, but Ginny did not like acid pops and since the Bertie Bott's Every Flavour Beans alone where less than 5 sickles she went with the money again. The third choice was more complicated since this time there was no money on either side. She had to choose between a dungbomb and three chocolate frogs. Ginny estimated that a dungbomb would be cheaper than the frogs and she would prefer the sweets anyway. She had almost started speaking before she remembered that Dungbombs were not allowed at Hogwarts and Fred and George would probably give her way more than three chocolate frogs if she could get them one, so she took the dungbomb instead. The next time Ginny choose the potion ingredients over some more sweets and then the standard book of spells grade 2 to 7 over 2 sickles.

After that no new things appeared in front of her. She looked around and saw that most of her classmates had acquired lots of sweets and some money. Rarely anyone had chosen potion ingredients or books.

Harry, after looking bemusedly at some of the options resumed speaking. "Alright, now that everyone has finished, please hand in your papers. I'll read them by next lesson and will give you some individual feedback if I think it will be helpful. For now, I'll just explain some general things you could have done. First of all this was a rather easy task since you only had to choose between objects. If you have to decide whether to practise for the next lesson or meet with friends things get far more complicated. We will come to these problems in a later lesson. If you have to choose between material objects, a good way to start is to think how much they cost. If one thing is worth significantly more than the other, even if you prefer the first one you will usually be better off taking the second one and selling it. However you also have to consider that this will take you time. You can usually also put a monetary value on your time, by asking yourself how much you would earn if you work during that time, this approach however does not work well with Hogwarts students since there is little opportunity for you to earn any money…"

Harry went on explaining different things you could do to adjust the monetary value of things to get a better result than by simply comparing how much the good would cost in a shop. Ginny was happy to find out, that she had thought of most of them. The only thing she had not thought about was that things she could use now would have a higher relative value than things she only needed later.

Harry had explained that this was only partially true in the wizard world since interest rates were not common in the financial system. However, he said, it was still relevant for them, because they would have access to a lot more money when they started working after Hogwarts. So having a Galleon now would be more useful for them than having a Galleon in ten years. After finishing his explanation Harry let them choose between different objects for a second time.

After that he told them that in real life you often were not absolutely sure what the result of an action would be so in that case you needed to work with probabilities.

He then started to teach them some basic math or what the standard Hogwarts curriculum would label "advanced Arithmancy". Most of her classmates were on a lower level than Ginny, so it was quite easy for her. Some of them however had serious trouble following Harry, and Ginny thought that it was a great idea of Harry to give everyone sweets and money before starting with this. Had he not done that, the classroom would probably have been a lot emptier. After the lesson had finished Ginny left and started walking to the classroom where her next lesson, Defence Against the Dark Arts, would take place.

To her astonishment all other first years and even the second years were headed in the same direction. For a while she thought this was a coincidence, but in the ever-changing castle of Hogwarts, you usually only had to go the same way as someone else if you wanted to go to the exact same place.

Ginny turned towards Harry and asked "What class do you have next?"

He paused, briefly looking at the swarm of students all heading in the same direction. "Defence Against the Dark Arts with Professor Lockhart. You?"

Authors Note

The next chapter will go online on Sunday July the 5th. After that I will have more time again and move back to a faster updating schedule.