The objective of the research was to find out the effectiveness of Peer Feedback practice in improving students’ writing performance of grade tenth in SMAN 3 Demak in the academic year of 2018/2019. The research design of this study was experimental research using quasi experimental design which belonged to quantitative method. The population of this research was tenth grade students in SMAN 3 Demak. The researcher used purposive sampling technique and two classes were taken as samples, they were X IS 4 as the experimental class and X IS 5 as the control class. The number of the sample was 36 students.
The instrument of study used was test. The researcher conducted pre-test and post-test. The Pre-test was given to both groups before giving treatments. The post-test was given after treatment was done. The data from two tests were scored used SPSS for Windows version 17.0 to analyze the result of pre-test and post-test.The result of T-test showed mean of experimental class in pre-test was 74.39 and mean score of post test was 79.17. After conducting experiment, the researcher gave post test. The mean score of control class pre-test was 12.61, and the post-test mean score was 15.61. It was indicated by result of pre-test and post-test in experimental class was sig. (2-tailed) 0.01 (p< 0.05). It means that H1 was accepted. It can be concluded that the peer feedback is effective in improving students’s writing performance of tenth grades of SMAN 3Demak.
Key words: Peer Feedback Practice, Writing Performance