Examples are an indispensable part of mathematical thinking through analogy, learning and the teaching process. In this study, the strategies that high school students used in example generation activities in mathematics course; operational and conceptual knowledge levels were determined and their effect on example generation ability was examined. The working group of the study was designed as a case study that followed a qualitative research method; the study consisted of 22 students attending high school in the 2016-2017 academic year. As a data collection tool, example generation questions were administered to the students. To analyze students' example generation processes in depth, semi-structured interviews were conducted and data obtained from the interviews were analyzed using a content analysis method. The results showed that the students used trial and error strategy more than transformation strategy while generating examples but no finding of analysis strategy was obtained. Factors affecting the students' example generation skills negatively included the lack of a mathematical equivalent of the concept images related to the topics covered by the questions and their not having a high enough level of concept knowledge. Results also indicated that conceptual knowledge had a positive effect on the ability to generate examples.