the cardinal rule

Sounds like you are having pretty good success breaking "the cardinal rule" as prescribed by all the other johnny come latelies, namely, "Use English. Don't use English to describe English." I have never understood that rule. You can use English to do all manner of things. You can use it to describe how to build a car, or you can use it to describe how to build a sentence. You are still using English. You can use English to explain that words have something that might be called a collocational field, change one word here and you'll likely need to change a word over there. You can use English to explain that there exists something called a Universal Grammar and yes, for christ's sake, you do need to be able to clearly identify the subject of a sentence. You can explain that modifying phrases and clauses in English tend to follow the thing they describe, unlike in Chinese where they tend to proceed it. You can use it to explain that words that might appear synonymous are still to be distinguished by their connotation. You can use English to explain that words are like people and it sometimes takes quite awhile to get to know them. In one situation they appear to mean one thing and in another they mean something quite different. Most words in English are homonyms and most have personalities. "Do" has a great personality and is sticking his nose in everywhere. Little bastard. "Have" is a clingy little witch, and even the dullest among us can be taught to contemplate buddha at the sight of "Be." They might not understand much of this so you can demonstrate using gestures, or say say it in Chinese before translating back to English. It's all quite charming really.

There was show on the discovery channel the other night about a teacher who therorized that it should be possible to create a genius out of anybody, and he set about proving it on his own daughter. I am not going to tell you what he did first because I want you to guess. It was a profoundly simple first step, and if you don't guess it before it comes along here you'll be enlightened when it does. It's REALLY simple. Did you get it yet? No? I'll just ramble along here awhile longer. Let your tired tired eyes whiz across the screen, perhaps it'll come to you.... If you want to create a genius out of anybody the first thing is to.... got it yet? If you want to create a genius out of anybody the first thing is to find out what they love doing.
If they don't love anything, and there exist on this tiny island an incredible number of sad souls who don't, introduce them to movies and music. Everybody loves movies and music, though perhpas they don't know it yet. Having gotten the ball rolling that way you can do all kinds of things, heck you can use English to talk about English if you want.