This study aims to find the Effect of Class Size on Listening Comprehension Skill of Iraqi Preparatory School Students. To achieve the aim of the study, an experimental research design was used in carrying out this study. For this research, random sampling technique was used. The sample for this study constitutes (70) Preparatory school students from Thi Qar Governorate during the academic year 2022/2023.The sample of the study is divided into two groups, a large group (45 students) and small group (25 students). The two groups were taught by the researcher. The pre-test and post-test of listening comprehension was applied to the two groups to assess the learners’ knowledge of listening comprehension skill and ensure its validity and reliability. Participants for this study were in 5th preparatory schools in ThiQar Governorate, Iraq. Two Preparatory schools were purposively selected from the Al. Nasir City. One of the schools had large class sizes with a combined population of 45 students for each class, another one had small class sizes with a combined population of 25 students for each class. After the application of the tools of the study, statistical tools were used to analyze the results of the study. To analyze the data, the present study was adopted the experimental design: Pre-Post-Tests control groups. The results reveal that there was a statistically significant difference between the mean scores of the experimental group and the control group. The findings of this study support the claims made by students that they learn more in smaller classes than in larger ones. Finally, the results were discussed and some implications for teachers and students were provided.
