This study is carried out to reveal which units teachers who encounter problems about falling behind the science course curriculum in secondary school in the 5th grade through the 8th grade prefer to focus on less and the reasons for their preferences. Survey model was used in the research study. Total 302 science teachers from 28 different cities in Turkey participated in the study carried out in 2015-2016 academic year. The research data were gathered via questionnaire form developed by the researcher. The results of the study revealed that nearly two-thirds of the science teachers spent less time teaching the units related to the "Earth and Universe" subject area to catch up on the curriculum in case of holidays, meetings, and exams held apart from the planned schedule. The units including ecology subjects within the subject area of Living Things and Life follow it. When the units are examined considering the grades, "Natural Processes" unit, the last unit of the 8th grade, ranked first. The reasons why science teachers put less emphasis on these units is the place/order of the units in curriculum, timetable of the centralized exam held in the country and timetable of the last written exams in schools, distribution of questions in the centralized exam, the number of gains from the unit and content, and the students' pace in understanding the subject.