The aim of this research is to determine the misconceptions among 6th, 7th and 8th grade students about the order of operations in line with arithmetic expressions and posing and solving problems related to arithmetic expressions. The research has a mixed-method research design with concurrent-triangulation design. The study group for the research comprised a total of 240 students with 78 from 6th grade, 80 from 7th grade and 82 from 8th grade chosen with the simple random sampling method from schools located in a city in the Eastern Black Sea Region in Turkey. The research used a two-tier diagnostic test developed by the researcher to determine the misconceptions of students. According to the results of the research, it was determined that 6th, 7th  and 8th grade students performed arithmetic expressions from left to right without paying attention to order of operations, stated that only operations in brackets need to be performed first in terms of order of operations, did not pay attention to order of operation when writing or solving an arithmetic expression equal to a given number, and that students had difficulty posing a problem sentence involving arithmetic expressions and requiring order of operations.

The aim of this study is to identify whether high school students encounter any difficulties in mathematics and reveal the reasons for such difficulties. The participants of the study, which was a descriptive case study based on qualitative understanding, were a total of 164 students, including 85 students from Anatolian High Schools and 79 students from Science High Schools. Approximately 11% of the participants said they had no difficulties in math, whereas 99% of the students from Anatolian High Schools and 78% of the students from Science High Schools said they had difficulties in mathematic. Their thoughts about the reasons for such difficulties were analyzed by content analysis method considering the type of high school they attended. The findings obtained revealed that the difficulties encountered by the participants in mathematics were teacher-, content- and student-based. Anatolian High School students stated that they intensely faced teacher-based difficulties, whereas Science High School students stated that they faced content-based difficulties. It's expected that the results of this study may contribute to studies to be conducted to increase student success in mathematics education and provide ideas for further studies.