With the introduction of the 4+4+4 education system in 2012, the school starting age has been reduced to 60 months and branch teachers started to attend classes starting from 5th grade. Therefore, in the current study, there are two aims. Firstly it is aimed to determine the opinions and experiences of science teachers having started to teach the 5th graders for the first time in the new education system. Secondly, it is aimed to determine the opinions and experiences of science teachers having started to teach the 5th grader students (including 9 years old) who started school in the 2012-2013 academic year and ranked 5th in 2016-2017. The current research study is a phenomenological study conducted on 22 teachers who taught to 5th graders in the 2016-2017 academic year and also had taught to 5th graders in the previous academic year. The data of the study were collected through semi-structured interviews. As a result of the study, it was determined that science teachers confront a number of difficulties in terms of teaching to 5th graders, and these difficulties increase with the number of students who started to school at an early age in a classroom. The teachers noted that students who start school at an early age are not ready to school both from affective and cognitive aspects. They also stated that they are required to deliver courses by making more activities and concretizing the subjects. As the teachers participating in the study also highlighted, regulating the school starting age to 72 months is important and necessary for both primary and middle school levels. [This article was presented at 26th International Conference on Educational Sciences.]