The effect of collaborative writing on the writing achievement of Senior High School students of grade 10

English has been used in many countries as an international language. In Indonesia, English is one of the most important foreign languages and it is an obligatory subject in some national and international schools in Indonesia. Therefore, it is taught to students in all levels. Realizing that writing is very important, the writer did a research on the students’ writing achievement using collaborative writing. In this study, the writer used a quasi - experimental time series design. The subjects of this study were the tenth grade students of Senior High School. The writer took one class as the experimental group and control group. The class was taught using collaborative writing for experimental group score and individual writing for control group score. Then, the teacher gave a writing assignment for both classes. The writing assignments were intended to measure the students’ writing ability in some criteria before the treatments. The treatments were given eight times ninety minutes each. The writer used writing assignment as one of the instruments to see the students’ writing ability and response of collaborative writing and individual writing used. After the writing assignments were evaluated, their means differences were analyzed using the paired t-test formula to see whether there is a different significant effect of students’ writing composition in their content, organization, and vocabulary. Based on the calculation of paired t-test, the writer found the significant value was 0.000