I don't remember ever having an in-class birthday party for anyone when I went to school. I remember in fifth grade we had a bake sale the day before Christmas Eve to raise money for whatever the school was raising money for and eating a brownie that I bought.
In the third grade, a class mother brought in sugar cookies in the shape of valentines for the class on Valentine's Day.
That's about it. School let out a 1 o'clock the day before Christmas Eve and the Thursday before Good Friday.
Oh, and when I was a senior in high school, the only teacher I ever had the most minimal personal conversation with in 13 years of public school education (three or four sentences) tossed me a piece of candy.
I don't know when this birthday party thing in school started either.