A review of graduate studies on numbers at preschool and K-12 level

The aim of this research is to examine the postgraduate thesis studies on numbers in mathematics education for pre-school, primary and secondary school levels in the context of their contents, tendencies and results. Within the scope of the research, 119 postgraduate studies including the keyword "numbers" in the database of the National Thesis Center of the Council of Higher Education between 1987-2021 were examined. In the analysis of the research data, content analysis technique was used in accordance with the nature of meta-synthesis, and descriptive statistics were used in the presentation of the data. According to the research findings, it has been determined that the number set tendencies in the postgraduate thesis studies mainly focus on rational numbers. The second most frequently used set of numbers in studies is integers, and the least studied area is complex numbers. It is observed in the studies that there is a tendency at the secondary school level the most. This is followed by mixed primary, high school, university, primary and secondary education levels. Findings show that there is only one thesis study on numbers in the preschool education period. There are quantitative, qualitative and mixed method tendencies in preschool and K-12 level graduate studies, respectively. In the theses dealt with in the field of numbers, it has been concluded that new approaches and techniques are more successful than traditional methods and that students' skills are insufficient and need to be developed. Based on the results of the research, it is recommended to increase the number of studies conducted at the preschool level, in which the foundations of many mathematical abstract concepts are laid in studies on numbers.