This research aimed to investigate student’s perception of assessment rubric, the influence of assessment rubric on student’s learning behavior, and what motivate student to do some particular learning behavior during writing activity. Using case study research design, the researcher conducted a comprehensive examination of a case through document analysis, direct classroom observation, and semi-structured in-depth interview. This study involves three students from one of the state university in Indonesia majoring in English Education Department. The data were validated by triangulation and analysed by following the interactive model analysis. The result indicates that the assessment rubric was valued by students as a guideline and standard reference providing assessment aspects and criteria. The assessment rubric also explains what is expected of students and how their work will be evaluated. There are six dimensions of student’s perception about the use of assessment rubric based on Waldrip study. Assessment rubrics influence student’s learning behavior by attentively listening, correcting peers, leading group discussions, and seeking confirmation from the lecturer. In contrast, the other students were inattentive to the lecturer's explanations and classroom discussion. Assessment rubric also influence student’s learning strategy. Student 1 implemented cognitive strategies; student 2 implemented social strategies; and student 3 implemented memory-related strategies. Furthermore, both students 1 and 2 mentioned that the assessment rubric motivates them in their learning process; they frequently ask questions, seek information related to the writing topic, and correct the wrong parts. While student 3 said that whether there is an assessment rubric or not, he still does the writing project. The findings of this study could be used for educators to continue to explore student learning behavior for better classroom management in language teaching and learning. In addition, well-designed activities focusing on learning behavior and learning strategy practices, along with the assessment rubric, must be established and communicated to the students.