Pedagogical agent is generally described as educational programs that guide, motivate learners while encouraging them during learning by providing feedback. The tasks (informative, guiding, or friend, etc.) and types (human-like, cartoon character, audio, text, etc.) of these modules can be classified based on various variables. Although computer-assisted instruction software is commonly used as a teaching material, research on modules integrated on such programs is scarce. Studies in the field have revealed that such computer-assisted instruction programs increase motivation of learners. In order to keep motivation levels high, these programs need to be adopted depending on the individual needs. Therefore, it can be beneficial to integrate software designed that can be personalized. In this respect, the present study was conducted with secondary school students to identify the impact of pedagogical agent on learners' academic success and motivation. For the purpose of the study, four groups were formed. The first group received education via fixed pedagogical agent, the second group had the option to choose among several pedagogical agents, the third group received the education without pedagogical agent and finally the last group received the same education through traditional (non-computer) way. This four-week program was introduced to students via MS Excel program and the data was gathered as pre- and post-test method. The findings have revealed that interfaces impacted motivation and accordingly academic success in a positive way. As a result of the study, it is suggested that learners should be provided programs that can be personalized depending on learners' needs and preferences.