Why Do 9 Year Olds Think They Know It All?

The same reason 19 year olds do. It's not until later in life that we (hopefully) acknowledge that others know more than we do!

They know from their parents or internet. Im 12 and i actually have a paying job as a mechanic and electricity technition. And i know pretty much everything to do with electricity, wiring, outlets, and all that kinda stuff. Oh and like handyman types of things i can fix almost everything

I know! When they're 8 and 9 they're going through a 'stage'.For girls they want to wear makeup, wear bras,have cellphones and have boyfriends, while in boys they want to be 'cool' and wear sunglasses, skinny jeans, have a girlfriend and own a phone. These years are sort of like 'previews' of there teenage life.

Because there smart

Maybe they were born like that or usually first smart then dump then smart.

Cause they do my cousin knows y=log xify= 10 then what is X

Because they have not fell down or walked into a brick wall lately. To remind them they need someone else to fix their boo boo's.aw!

Well when i was 9 year old i just felt like i always needed to be right for some reason idk but now that im older i understand even if you know it all you still need to ask questions=]