I was at a birthday party for a five year old. When she opened presents, it was quite obvious when she didn't like something. She opened many presents, set one aside without bothering to look at it and say thank you. She actually opened one, rolled her eyes, and sighed with disappointment. When the present-opening was over, she never thanked anyone. Do you find this behavior appropriate? Do you think it would have been good to say, "you should say 'thank you'?"