Cos my son is 10, and not 5 like my daughter, he didn't invite the whole class to his birthday party, just 5 or so friends.
10 year olds are so refreshingly unbitchy, tho: he invited the 5 kids he most wanted to hang out with. I was the one saying, "Don't invite her, she didn't invite you to her party - and he never apologised for tripping you when you were both 7."