This study explores the features of sociocultural context of experiment classes taught by a science subject teacher. Two experiment classes on electric circuit for fifth graders were observed and video recorded. The data was also collected through student interviews and teacher interviews. Using the cultural historical activity theory, we extracted the six sociocultural factors and analyzed their interactions. This study could identify that four features of the sociocultural context of the cases. First, the rules of science classes were not decided by the teacher, but formed and modified through the negotiation between the teacher and students or between the students. Second, elementary students played a game, i.e. 'Countdown game', during their electricity experiments, which had both positive and negative influences on science learning. Third, the science teacher feels a limit on life guidance because of the position as a subject teacher in an elementary school. Lastly, although the science teacher had enough time to prepare science classes, there was no guarantee of the improvement of teaching quality. Based on the results of this study, educational implications are discussed in terms of teaching science experiments and of the science subject teacher system.