Teachers need to thoroughly understand the subjects they teach. In some cases, teachers are tasked with teaching unfamiliar content for various reasons. To ensure pre-service teachers are well prepared, higher education teacher training programs should integrate unfamiliar content knowledge into the required microteaching sessions. The purpose of this exploratory qualitative descriptive study was to explore how university professors who instruct teacher training courses reflect on their perceptions of pre-service teachers' content knowledge when they assign unfamiliar content topics to the pre-service teachers' microteaching sessions. This study was guided by one research question: How do university professors who instruct teacher training courses reflect on their perceptions of pre-service teacher content knowledge when they assign unfamiliar content topics to the pre-service teachers' microteaching sessions? Kolb's experiential learning cycle served as the foundation for this study. The data collection source consisted of a pre- and post-microteaching questionnaire. A simple thematic approach, as described by Braun and Clarke, was used to analyze the data for this study. Three themes were identified from the thematic data analysis: (1) comprehensive content knowledge, (2) familiarity and preparation, and (3) comfort versus challenge. Practical classroom implications and recommendations for future research are included.