You should say:

　　What subject the teacher taught you

　　When you had his/her class

　　Describe the teacher’s appearance and personality

　　And explain what effect the teacher had on you.

　　First let me tell you about my teacher Zhang Fei and she still works at the Dalian Middle School number 23. She taught me English in school. I had her class about 6 years ago and she taught me for a full year.

　　First let me tell you how she looks. She looks very normal except that she’s very beautiful inside. She’s tall and thin but the thing you can notice about her wonderful, dark eyes with very bushy eyebrows under her spectacles. I can still picture her. You know she does not seem friendly at first, because she is very stern when she speaks and she will not tolerate nonsense, but she is very kind in her own special way. . She is also very demanding and clear when she speaks and her concern is not so much your grades but your effort.

　　The effect she had was very powerful. Essentially she taught me that you could be very disciplined and stern and hard working but still be very kind. Before I thought all teachers who were strict were just mean. After her, I learned that hard work is about not compromising on quality.