anger reaches the body first

Anger does not begin in the voice. It arrives one floor below — the jaw sets, the hands close, something tightens behind the chest bone. By the time it reaches the throat it has been in the building for several minutes.

The skill is not "don't be angry." Anger is weather; it will come. The skill is noticing it at the jaw stage instead of meeting it at the shout stage. At the jaw stage you have choices — a breath, a walk to the balcony, the second half of the sentence said softer. At the shout stage the choices have mostly been spent.

Teach your child none of this. Children do not learn noticing from lectures; they learn it from living with someone who unclenches.

Tonight, once, unclench the jaw on purpose. That is all.