I just love this course and tell everybody about it at the Chinese school where I have a 2 1/2 hour-lesson once a week. It complements and puts me several steps ahead of my presential classes - everybody feels awed by the sentences I'm able to build, my vocabulary and sometimes the explanations about a certain term that even the Chinese teacher is not able to explain (sometimes it's difficult for a native person to explain the mechanism of his own language, because it's just so intuitive and automatic for him).

What you are doing right and the others aren't is two fold.

First of all, you have a progressive series. A person can actually start from the beginning and work their way up to a conversational level. All the words are accounted for. You remind people of what is new and what has been covered already. You remind them in Chinese and use English sparingly.

This is the way that it should be done. After the initial stages, a language should be taught in the target language as much as possible.

The second thing – Lessons are introduced in Chinese.