Bright doesn't mean wise.
A child needs to know that he's a child in order to have a foundation on which to build a successful adult life. Treating a child as a miniature adult is really not helping the child to grow.
Sometimes children are very bright and very perceptive, and we can make the mistake of thinking they are wise. We may treat them as confidantes or peer. But by definition, a child's opinions, no matter how bright, are not wise. They are not based on the kind of knowledge Judaism calls da'at. Da'at is a maturity of the mind, an ability to make connections and perceive the consequences of one's ideas, but without da'at, those ideas don't connect with the real world.
A child before Bar or Bat Mitzvah, is not a Bar Da'at. They may have alot of sense and intelligence, but not da'at. That's why their behavior doesn't necessarily correspond to their level of understanding.
So if you want to share knowledge with a precocious second grader, teach him eighth grade math. But never debate the ground rules for behavior; that belongs strictly in the realm of the adult who has da'at, and has learned wisdom from experience.
There's a certain comfort for children in knowing that they can listen to and trust an adult's judgment. If a child wins a debate with parents, not only will the parents be distressed, but so will the child. That doesn't mean that you have to disagree with them. If they come up with a good suggestion, listen and genuinely consider it. You might say, "I thought about what you suggested and I've decided that we should do it." But the decision about what to do should be yours.
Never say, "Okay, you're right." That leaves them with the responsibility for their judgment, when you are the one who should take responsibility. And if you act on the idea an dit doesn't work out, continue to take responsibility. Compliment your child for the idea, but provide the security of knowing that an adult gave the final approval.
IT TAKES TIME TO GET IT RIGHT
We expect both too much and too little of our kids, mixing up normal maturation with moral development.
There's a big difference between behavior that reflects a child being a child, and behavior that is inappropriate for a child. One of the most frustrating things in childrearing is when you tell a child something over and over again - not to climb up to the cookies, or not to make a mess - and he keeps on doing it. Inappropriate behavior must be stopped, but if the child is merely being a child in spite of your expectations, then change your expectations.
Make sure not to get it backwards. There's the parent who knows that the child lies and exaggerates and lets it go. If the same child takes some cookies when he's not supposed to, or spills something at the table, it's a disaster and he get spanked. A child can't not spill and a child can't not go for the cookies, it's normal.
But if a child is lying, it isn't safe to let it go, saying, "He's just a child, he'll outgrow it." Because adults lie, too. You can be confident that the child will outgrow the juice on the shirt, but he or she may never outgrow the lying.
When it comes to morality, we have to create expectations and we have to have the courage to put some teeth into our expectations. Even a good child with good ideas needs your authority to be able to do what is right. Telling them what's right is not enough because they already know; you've told them before and they are not lacking the information. What they are lacking is da'at.
If you consistently condemn and reject a wrong act, like lying, then the child realizes that what you've been saying is not just theory. It's the truth, the way to be. If a mother is horrified that a child did something wrong, that's what the child needs to see. He doesn't need to be told that it's wrong. Not after the first time. But to see that you are horrified, to see that it hurts you, to see that you are disappointed, that you can't get used to it, you can't make peace with it - that in later years, will be the teeth behind the child'sown values. Meanwhile, we don't reject them for not getting it right, becuase we understand that they are children.
The ideals eventually become the child's own. But until that happens, the child goes along with your agenda. That's what it means that you are responsible for your child's sins until they are bar or bat mitzvah.
The right balance to maintain is that you recognize that a child may engage in immoral behavior such as lying, yet you also recognize that now is the time to start changing it.
When we think about it, this is the parenting technique, so to speak, that G-d uses with us. Three thousand three hundred years and some ago, G-d told us not to lie. After that, He sent us a prophet. Over and over again, many hundreds of prophets came to tell us, "Do what you were told to do. Keep the commandments." G-d knows that even after He's taught us right and wrong, we're not going to do it right; we're children and we're human. So He repeats it, but He doesn't throw us out of the house. We need to do the same with our own children: to teach them right from wrong forty times, but then not to be surprised that they haven't change yet. Ultimately they will change. Our frustration with kids still being kids after we've told them forty time is not kosher. We don't have the right to refuse ourkids their childhood.