I played Raymond Keene just after he'd become British champion when I was 11/12 in a simul after a tourney and the schoolteachers who had organised it came and murmered in my ear that I should resign - I was winning !!! so I refused Keene was spending ages longer at my board than any of the others, including his protege Julian Hodgson's
It was a very complex position which was obviously beyond the understanding of the 'adults' apart from Keene himself.
Eventually we drew, but I still believe to this day that I wudda won iffen only the bloody 'adults' had left me alone an' not constantly distracted me - I was spending my thinking time explaining the finer points of the position and the various combinations to these bloody patzers
My point being, that no one should ever underestimate anyone - I sure as sugar didn't when I played Luke McShane when he was only about 8, an' just as well, I only just scraped the win - an btw he was perfectly grown-up about it - don't think I ever met a child with such maturity
"I hate it when people just assume that because you are 11 like I am that it will be an easy win. Why do people actually think that age makes that big a difference?"
The "people" you are refering to... are they adults or teenagers?
Teenagers were 11 years old just a few short years ago and they KNOW that they have improved since then. They are assuming that you played as bad as they did when THEY were eleven.
Let them think what they will...it doesn't matter in chess, you can prove them wrong by beating them!!! The more that a person believes that an 11 year old chessplayer is going to play bad, the more their ego will be crushed when you beat them.
Try not to "hate it" but use it to win, Those "people" will be more nervious about losing to you than you are of losing to them...And... if they are better than you, they may accept a draw more readily than risk the embrassment of losing.
As anyone gets older and more experianced in chess, they learn to RESPECT their opponent regardless of their age.