Make it a competition
When I first came to China to teach in 2003, I made plans for all manner of problems I would encounter. I bucked up on independent clauses, dangling modifiers, and the subjunctive (If I were to be a good teacher, I knew I would need it). Upon arrival, however, I found the largest dilemma in my classes was something far more general, and far less easy to solve with a simple grammar textbook. Despite the fact that each of my students had been placed in the “advanced” English class, they ranged more dramatically in their ability than I ever had anticipated. In my experience since, this range in ability exists across universities, primary schools, private training centers, and anywhere else you may find yourself teaching in China.
In these situations, the path of least resistance is always to teach primarily to the best students in your class. They will be sitting front and center, expressing great interest in what you have to say, while their less English-friendly classmates will drift toward the back (or not come at all). The best students will seem more interesting and will pad your ego, while the others will appear bored and ungrateful (sometimes unconscious). To be a responsible teacher, however, requires that you find effective ways to include this group of students without sacrificing the experience of those sitting front row center.
The most effective solution to this problem I have found is to introduce elements of competition to the classroom. In general, your weakest students are likely to be male. Creating games that can be won and lost tends to be the best way to pique and keep their interest. Game shows like Jeopardy can easily be transferred into an oral English setting, but usually you will find that with some slight tweaking, virtually every single class plan can be made competitive.