Let's face it, teaching kids manners can be a challenge, especially three year olds. My three year old has a particular amount of sass, which I am hearing is not unusual for a three year old.(right?) But we started early on the whole manners thing. "Please", "Thank You", and "May I" are three terms we constantly instill with the kids.
I have a friend who is challenged with how to discipline her children. I think her challenge isn't the discipline per se, but the follow through and execution each and every time. Consistency, consistency, consistency is the key. Cookie is not allowed to get up from a meal with out asking to be excused, each and every time. We will not get Cookie food, drink, toy, or anything with out a "please". It was difficult at first, but we continued to correct, now she just needs a look or "what was that?" to self correct. And of course we always need a "thank you."
Cookie is three, so right now our challenge is the "I don't want to" and the "I WILL!" with attitude, which we keep correcting to, "yes, Mommy." I can see how someone wouldn't want to fight with their kids every conversation. But really, after the first week of forcing the issue, we really don't have a fight. We just tell her it is polite and the correct way to say something. Or we give her a look or the right term and she will then repeat.
How do I know it is working? The other day Hubby and I went for a bike ride with the kids. We ended up at a park, and in playing "baker" in the sand, Cookie told me very politely, "Mommy, your cake is ready, please come pick it up." When I appeared at her delivery window, she asked for "Five dollars, please." I "ate" my cake and thanked her for the delicious concoction which she promptly replied, "thank you for coming today." We have never ever played this before. I am not sure if she played something like it at summer camp, but I had a mommy proud moment. My daughter had manners.