Residence Permit question (Beijing)

I have heard all about the extra checks of people's visas, including what they are doing, and its made me wonder what my situation allows me to do.

I am a UK citizen who is married to a Chinese National (and have a Chinese son). We registered our marriage in Protected content Changsha, Hunan, and until Protected content lived in the UK. We returned to live in China at that point, and I first got a visitor's visa saying that I was travelling and staying with my wife. 18 months ago, I got a yearly residence permit which I have renewed, and hope to get a permanent residence visa as soon as I am able to.

Now, I know that this residence permit acts like a multiple-entry visa (and I have used it as such without any problem), but does it also function as a general-purpose work permit as well? If not, what do I need to do to also be able to get a job? (I'm thinking of doing teaching at various universities, teaching one or more course at separate universities, as I have been asked to do this on more than one occasion previously).