This study investigates how prior content knowledge and prior exposure to microscope slides on the phases of mitosis effect students' visual search strategies and their ability to differentiate cells that are going through any phases of mitosis. Two different sets of microscope slide views were used for this purpose; with high and low colour contrasts and students' ability of recognition were investigated. Study group was consisted of forty undergraduates majoring in science teacher education at a major university in Turkey. All participants were considered novice microscope users based on their ability. Participants prior content knowledge was assessed with "Mitosis Inventory" and they were grouped based on their level of prior content knowledge. High and low level content knowledge groups took part in the study. Based on the results of the eye-tracking data; prior content knowledge was found to have an effect on participants' visual search strategies and their recognition time for the slide samples that were in high colour contrast. High prior knowledge group was able to recognize and identify the phases of mitosis correctly in a shorter period of time in comparison to low level prior knowledge group. However, no difference was found between groups for the low colour contrast slides. (Contains 2 figures and 2 tables.) [For the complete proceedings, "Proceedings of the International Association for Development of the Information Society (IADIS) International Conference on Cognition and Exploratory Learning in Digital Age (CELDA) (Madrid, Spain, October 19-21, 2012)," see ED542606.]