Our children need us to be their rock. They need to be able to borrow our calm. When our child gets spun up in an emotional hurricane, it is counterproductive to get into the hurricane with them. The two of us in a cyclone equals disaster with no resolution. When we do this we are actually telling our children that yelling and screaming and throwing a fit is okay, regardless of what we say.
We no longer present ourselves as emotionally mature adults. Quite the contrary. Our emotional maturity now matches the emotional maturity of our child- the child that is yelling and screaming and carrying on in a wild way.
Positive discipline is scream free discipline. Rules are established. Children know the consequences for breaking those rules. Children also know that they have a choice- follow the rules or lose a privilege. This can all be done without screaming and yelling.
When your child is feeling out of control, they need to know that someone is okay. And that someone is you. They need to feel secure knowing that you are stable while their world feels rocked. They need grounding. They need a calm presence in the middle of their chaos. By getting calmer as they get louder, you are modeling appropriate behavior. And modeling usually is the best teacher.