OK, I see a lot of people trying to relate their classroom experiences to how they like their Mandarin classes to be taught. But seriously, for older kids I think the situation is quite different.
We choose to learn Mandarin voluntarily, and when we learn it it is - 90% of the time - the ONLY thing we are learning. Sure, we also have a job but it doesn’t come close to the kind of pressure the Taiwanese educational system puts on these kids.
I know I am stating the obvious, but these kids study English as just one of many other subjects. Additionally, they go to cram school for most of their primary curriculum subjects. When these kids come to cram school (and maybe to a lesser degree to elementary school) their minds are exhausted because they have been learning since god knows what hour in the morning. Couple this with pressure of monthly tests and the pressure of qualifying for the best school and you have a tired mind that never gets a break.
The point I am making is that their minds are so fatigued that they will often have great difficulty listening through everything you say in order to find words that have some kind of meaning to them. Sure, English is still the general rule, but a little Chinese can help because some English words or phrases are damn hard to understand if only explained in English. I mean, how many kids actually admit to a lack of understanding. Even if the all say, “Yes, I understand”, I doubt that all of them do. They are too afraid of saying, “No” because they will lose face.
So, some Chinese is an absolute necessity with hard to explain English, especially given the amount of material that some schools try to cram into their lessons. Have you ever tried to explain things like “Even if…” using only English without sacrificing valuable class time (takes 3 minutes in English if you are lucky, but 10 seconds in Chinese).
For the little tots, though it’s different. Although they have nowhere near the same kind of pressure, they need some Chinese to help break the proverbial ice that covers the slippery slope to learning English. But, thats about it, and after a few months their minds can cope with things and English takes over in the way things are taught. That’s my opinion, anyway…