Discovering process of a plant hormone auxin contains the science history of research conducted by many scientists for more than 50 years. This study is aimed at developing a teaching program by determining the science history of the discovering process of auxin and arranging its findings chronologically from pre-Darwin era to post-Went era. The developed teaching program was then applied to the class of sixteen 11th graders to analyze the effect of students` concepts on auxin as a plant hormone and how their attitude towards science and their understanding of science had been changed. Based on the literatures regarding the discovering process of auxin, this study developed the teaching program containing 4 sessions. The 4th session specifically focused on the open investigation method in which students could set hypotheses at the stage of raising questions by using corn coleoptiles, design and execute tests, analyze their results, and make conclusions. This helped students experience the process that scientists in the past adopted for their research. While students explored the developed teaching programs, they could acquire the concept of plant hormone auxin precisely. Just as the scientists` concept on auxin in the past had been changed, students` concept also changed from as an electrical potential to as a material. While students` understanding of scientists in the past was changed, their attitude towards science became proactive and positive. There were also various positive changes observed in the affective domains. Therefore, it could be said that the developed teaching program presented a positive effect on students in the affective domains by helping them experience the research process and effectively make up the concept of plant hormone auxin.