The study deals with the variation of Turkish students' reading comprehension performance according to perceived teacher support and reading activities in the classroom. This study, which is grounded on the data drawn from the PISA 2018 database, investigates the relationship between certain variables. In the analyses performed on the PISA IDE server, the PISA 2018 reading literacy general averages of Turkiye were associated with the identified variables, and the differences in the averages were examined. As a result, perceived teacher support, teacher's adaptation of the course, and stimulation of reading engagement have a positive relationship with reading comprehension; however, it was found out that the frequency of receiving feedback had a negative relationship with reading performance. In addition, the general reading average of the students who reported that they had not performed activities such as summarizing, comparing the content of the text with their own experiences, comparing the text they have read with other texts written on similar topics, and writing about the text that has been read was much higher than those who reported that they had performed these activities. These results have strengthened the conclusion that teachers give feedback to poor readers more frequently. On the other hand, it is possible that good readers may find the learning activities in the course inadequate. In summary, reading comprehension performance is positively or negatively affected by teacher support, adaptive instruction, feedback, and engagement in reading activities in the classroom.