An idea for parents that believe spanking is necessary.

Comic Foreground

When a child does something "forbidden," the parents could take the beating on behalf of the child. Instead of being the recipient of the beating, the child must simply watch parent take the beating from behind a Comic Foreground (or faceless standee); i.e., the kids will only have to see the the parents face wince in distress from the beating and of course hear the sound of the impact.

So long as the kids are able to understand the, cause and effect, link between their behaviour and their parents pain, they'll know that it's within their power, to privilege their parents, a pain free life. Because taking a beating isn't a taxing as watching someone you love take a beating for you.

Schools can incorporate this method too, it'll make for an exciting parents evening.