Skill of fifth grade student of Cipinang Muara 06 State Elementary School in writing report is still low. This is evidenced by the average scores before giving the action, which is 68.66. The average score of students who are still below the minimum completion criteria is due to poor students in writing sentences in accordance with the correct structure, the sentences are not structured in accordance with the Indonesian Spelling, the selection of standard words is still not quite right. In addition, students have not been able to write a factual report, the written report has not been coherent and has not explained clearly the events observed. In addition, teachers are still applying classical teaching methods with lecturing and assignment methods that are based solely on guidebooks only. This causes students to be less motivated so they have not been able to improve their skills in report writing. Learning to write observational reports made in class makes the students less able to write reports in accordance with the conditions and facts about the things that must be considered in writing the report. The formulation of the problems contained in this study are (1) How the project-based learning method can improve the skills of writing reports to students in fifth grade at Cipinang Muara 06 State Elementary School; and (2) Will the project-based learning method improve the writing skills of the students in fifth grade at Cipinang Muara 06 State Elementary School? The purpose of this study is to describe the process of learning to write observational reports during the use of project-based learning methods, the skills of writing student observation reports after using project-based learning methods, and changes in student behavior after following the learning of writing observation reports through project-based learning methods to students of fifth grade Cipinang Muara 06 State Elementary School. This study uses a classroom action research design. Subjects in this study were fifth grade students that amount 29 students consisting of 15 male students and 14 female students. This study consists of two cycles. Each cycle consists of several stages, namely planning, action, observation, and reflection. Data collection was done using test techniques and nontest techniques. The test technique is used to know the quantitative results. The result is obtained from the test of students' writing skill, while nontest technique is used to collect student activity data during the learning process. Nontest techniques were obtained with observation guides, observations of student and teacher activities, as well as video and photo documentation. The data analysis technique of this research is qualitative and quantitative. The results showed that there was an increase in the process of learning to write observational reports during the use of project-based learning methods. The improvement of the process is evidenced by the result of the students' writing skill skill which increases in cycle I and cycle II, besides the learning of writing the observation report which more smoothly in cycle II and the more conducive classroom atmosphere. The skills of writing observational reports increased after using project-based learning methods. This improvement is seen from the students' learning completeness which reached 51.73% in cycle I and increased by 93.11% in the second cycle with an average value of 82.28. In addition, the increase occurred in the behavior of students after following the study writing observation report. Students are more active in learning because learning is more interesting. Based on the results of the research, the use of project-based learning methods can assist students in writing observational reports because students can put their ideas and ideas into a writing based on observations that have been done directly so as to increase students' writing skills in writing observation reports.