Harry was a very bright boy, even at the young age of fifteen months he had a basic understanding of English. Dispite this he did not yet have a very good judgement of what is true or not, then, what fifteen month old does...
The same day that he was picked up from the doorstep to Nr. 4 Privet Drive, Little Whinging he was told by both his uncle and aunt that he was a Wizard.
The second thing he was told was when he got hungry, he was told that Wizards does not need to eat, and not knowing it was a lie he accepted that as truth.
The third thing he was told was when he got tired and wanted to sleep, he was told that Wizards does not need to sleep.
So instead of getting a bed to sleep in he was sent out into the garden and was told to remove the weeds that had collected there over years of neglect.
The fourth thing he was told was when a gust of wind made him cold and he wanted clothes, he was told that Wizards make their own clothes from thin air.
A couple of hours later he was told the fifth thing, it was getting dark and he wanted some light to be able to see what he was doing, he was told that Wizards can see in the dark.
It was about a month later that he was told the sixth and seventh thing, that was a couple of hours before he got to meet the first person outside of the Dursleys since he was dropped off at their doorstep, he was told that no one can know he is a Wizard outside of the family and that Wizards can clean them selves and other things by just wanting it to be clean.
He was told the eigth thing just before being told to make food for the family, and that was that Wizards can create great tasting food from thin air, this was shortly after his third birthday.
The ninth and tenth thing he was told spread out over the years before he was old enough to go to school, he was told that a Wizard never forgets and that a Wizard can speak any language without being taught.
He was told the eleventh and twelwth thing just before his Aunt and Uncle drove Dudley to school, and that was that Wizards always gets perfect grades in school and that Wizards does not need to get a ride to school, they get there by them selves.
A couple of weeks before his eleventh birthday he received a letter from Hogwarts, he sent a positive reply about it when he was told the thirteenth thing about Wizards, Wizards can be in two places at once so they can both go to Wizard school and regular school.
Later in the week when his Aunt took him to get his supplies for Hogwards she told him the fourteenth thing, Wizards create their own money, but pretend that they don't.
Following the eleventh thing about Wizards Harry got a lot more books than was listed on his supply list and then payed with the golden coins that he created inside his trouser pocket.
During the next month he discovered a lot of things that did not match up with the things about Wizards that his Aunt and Uncle had told him and with what was written in the books that he had bought.
He then understood that none of them were Real Wizards.