Wish I'd seen this sooner!
Kindergarten classes (if a training centre is parachuting you in) are a burst of singing and quick games, punctuated by use of new vocabulary, phrases and modelled dialogue- in English class.
For the full time teacher of the class, there will also be math, PE, music appreciation, science, dance, geography… stuff about life. But the main teaching will be between lessons, as the kids observe and mimic your behaviour. After all, for most of them you are the first adult they know outside of their home. They will absorb your attitudes, way of treating others, habits of speech, grooming and cleaning, etiquette…
As the others have said, it's a very tiring job. But it's more rewarding than anything else I've done- and I've pretty much done it all. The difference between the little buggers you start out with in autumn and what they grow into by summer, well, it's humbling.
I've noticed that these gigs don't pay as well as they used to, but they're still pretty lucrative. It's a small subset of laowai teacher who is willing to take these gigs on, so there are always positions out there.