The purpose of this research is to determine the sources of cognitive and metacognitive strategies that 7th-grade students use when studying the "Cell and Divisions" unit that belongs to the field of Biology. In the study, the case study which is one of the qualitative research methods was used. A total of 6 students from 3 different secondary schools in Kars participated in the study. In the research, 6 7th grade students who study in 3 different secondary schools read the "Cell and Divisions" unit in the 7th grade Science Textbook. Students were observed by the researcher in their process of reading this unit. Students were asked to think aloud to determine the cognitive and metacognitive strategies used in the process of reading the unit. To determine whether the strategies used in reading the unit are cognitive or metacognitive, and to determine the sources (from, where or how) of these cognitive and transcriptional strategies they are using, semi-structured interviews were conducted with them immediately after reading the unit. The observation records of the students' reading process of the unit and transcripts of the data obtained from the semi-structured interviews with the students after reading the unit were made. The transcripts of the data were analyzed. According to the results of the research; It was determined that the sources of the cognitive strategies used by the two students who study in the 1st secondary school and have high grade point averages while reading the "Cell and Divisions" unit were themselves and their teachers and the sources of metacognitive strategies of them were their teachers and friends. It was determined that the sources of the cognitive and metacognitive strategies used by the two students who study in the 2nd secondary school and have medium grade point averages were only themselves. It was determined that the sources of the cognitive strategies used by the two students who study in the 3rd school and have low grade point averages were only themselves, But it was determined that the sources of the metacognitive strategies of one student were himself/herself but since the other student did not use metacognitive strategies the sources of the strategies could not be determined.