This paper reports a qualitative research that identifies the characteristics of good mathematics teaching from the perspective of Mexican high school students. For this purpose, the social representations of a good mathematics teacher and a good mathematics class were identified in a group of 67 students. In order to obtain information, a questionnaire was applied with open questions and focus groups with three or four students were organized. The answers to the questionnaire were analyzed by locating categories that consolidate a specific social representation. The information collected in the focus groups contributed to shedding light on the meaning of the words, phrases, and notions of common-sense knowledge used by the students. The students consider a good teacher to be someone with knowledge and who knows how to transmit the knowledge; someone who provides a step-by-step explanation and does not leave doubts in the minds of the students; someone who is patient/comprehensive and someone who does not make classes tedious/boring; someone who teaches in a simple and fun way, and arouses interest in students. In a good mathematics class, you are not bored, you learn; there are good, varied explanations and lots of exercises and students participations.