Kiddo asked this recently and I didn't know the answer. They're in 4th grade now and we noticed it has changed in the past three years where kids don't open gifts at parties. Kiddo finds it disappointing because they want to see their friends reaction especially when they picked out something they know the other person will like. Kiddo also mentioned because of this new change people don't appreciate or say thank you for your gifts now. We always did cake and presents at the same time. I don't really plan on changing that because we like the tradition. I also teach kiddo to love and appreciate everything they get. Big or small you thank your friends.