This study investigated the evaluation of science activities held over one day at the natural history museum (NHM) in a rural part of Turkey. The purpose of the research was to determine one day science activities in NHM through students' expectations, observations, feelings, learning experiences, and their effect on their academic achievement and explore teachers' views about the process. Middle school students (n=125) and their teachers (n=8) participated the activities. Qualitative dominant (QUAL+quan) parallel convergent design, one of the mixed research methods, was used in the research. Four different data collection tools (achievement test and three semistructured interview forms) were used. According to the results, the activities had a positive effect on the academic achievement of middle school students. It also helped them gain more profound experiences about the components of nature and develop more positive emotions. Prior to the science activities, the students expected to focus on observations and examinations. They emphasized the activities they conducted to collect and analyze fossils more strongly after the completion of activities. Teachers stated that science activities in the museum increased the active participation and interest of the students compared to the classroom environment and enabled them to provide awareness towards the environment and science.