I am currently working at Hua Language Centre teacher and have done so for 4 years, teaching P4-6, Sec 1-4 (incl 'O' level class).
My private tutees have ranged from students of top local schools (e.g. NYGH Sec 1 to 'O' level HCL, RGS 'O' level HCL) to 'N' level students, as well as international school students at the Singapore American School.
In 2012, 2 of my RGS students scored A2s in HCL despite having B4 to C6 range grades previously. In 2014, my PSLE student went from failing Chinese throughout upper primary to getting a B in PSLE despite getting ungraded in other subjects.