I have taught a few secondary student who are really weak in their sciences and maths. Because i am very familiar with the contents, i have many techniques and methods whiche i can share with them and let them know the correct way to approach the subject. As a result of my useful teaching, they have done very well in the science and math in "O" level.
I also spoke fluent chinese and english.
This is because i am from China but i have been here for more then 10 years. Hence i am teach kids chinese very well, especially if the kids are very poor in English.