How to volunteer ESL services ?

Hi,
I am a 27 year old (female, Canadian) certified ESL teacher and I am moving to Hong Kong next month to teach and model. I have heard about the extreme poverty in some parts of Hong Kong and was wondering if anybody knows legitimate means of going about finding families/children to volunteer teaching services to on some of my off hours. I am moving to Hong Kong because I will be making a good amount of money and I'd really like to spend some of my off-time giving back to the children of Hong Kong that would never be able to afford the type of private school I will be working in. Even something like a "big brothers/big sisters" program because I'd love to really positively impact the children I'd interact with/ brighten their day by being able to even take them to the movies/ ice cream/ etc. that their family might not be able to afford. I am not sure if these things are really normal in Hong Kong but I taught in Bangkok last year and had a kindergarten student I bonded really well with and used to do these things with her (her parents were constantly at work and barely spent any time with her themselves) and it was a really rewarding experience to have such a positive influence on her life while I had the means to. Any help pointing me in the right direction if any of you are doing/ heard of something similar please let me know!!
- Brittany