I found this great article by Elisabeth Elliot called A Child's Obedience on Michelle's sidebar at This One's For the Girls (she's really a fount of information and that sidebar is a great overview of her parenting wisdom). It's short, and I highly recommend you checking it out. You can read it now. I'll wait.
The short article talks about training your young toddler to obey. It seems quite simple to me, and I think it will work. Kyle likes to do things his way, but he is fairly trainable. Given the problems I've had with Amanda this summer, I think that this will work as a way to train him to listen and obey--the first time--but I think that it will train me to be a better disciplinarian. You see, I am learning that it's really all about me.
As far as Amanda, I am implementing this for her as well. I'm thinking that perhaps an immediate time out every single time she doesn't act immediately or speaks disrespectfully might work. I know that for a 3rd grader, "time out" seems like a weird punishment, but she loves to be in the midst of everything, so sending her to the stairs for just a few minutes is an effective deterrent, and if nothing else, it gives her a chance to reflect and regroup mentally.
So far, so good, but I know that it will require me to be consistent. All the time.