In the third chapter he talks about the two unhelpful and extreme responses to anger. The first is to blow-up and the second is to internalise. He suggests that anger is an emotion that has the purpose of destroying something. Instead of destroying ourselves (by internalising) or others (by blowing up) we need to destroy the problem that created the anger. And we destroy that problem (as usually anger involves other people) by communication.
Communication, he suggests, involves not only words, but also our tone of voice and the expression on our faces. When teaching children to deal with their anger, they have to learn not just what to say, but also how to control the tone of their voice and the expression on their faces.
All this rings true for me when I think about how I respond to anger (I'm definitely an internaliser and need to work hard at talking about it) and I know from observing my children that tone and expression can convey much more than words.
In the fourth chapter he introduces The Gumnazo Principle, by which he means 'training' (Gumnazo is just the Greek word for it, apparently). He says
...be sure that you clearly understand The Gumnazo Principle; biblical discipline involves correcting wrong behaviour by practising right behaviour, with the right attitude, for the right reason, until the behaviour becomes habitual. (p66)
He distinguishes between teaching and training like this; teaching gives knowledge while training gives skill. There's a lot of overlap in the way we use these words but I understand his point. When it comes to behaviour, its not enough to teach, we must train. We train our children in righteousness in the same way that a master trains his apprentice rather than as a lecturer divulging knowledge to his students. And training requires doing it again and again and again and again until it is learnt.
I think I do expect to tell my children once and subsequently they behave the right way, and get cross (and expasperated) with them if they don't. It was helpful instead to view this as a process. Right behaviour is something they need to practise, particularly when sin will be pulling them in a different direction. I am thankful also for the work of the Spirit in their lives!