Scientific argumentation skill required to be mastered in this era. Unfortunately many students still have strunggle improving their scientific argumentation skills. This study was aimed at describing the effectiveness of ecosystem module grounded in Problem-Based Learning in improving scientific argumentation skills. This research was part of the field testing of R&D, a research and development previously conducted. Research participants included tenth grade senior high school students. Two classes were selected as a control and experiment class. The control class (existing) did not use the module but the experiment class use the module (module class) grounded in Problem Based Learning implemented. Data were collected from written tests and observations. Data analysis used the scoring rubric of scientific argumentation skill aspect which their results were tested with Gain test and independent T-test. The findings showed an increase in scores of the four aspects of scientific argumentation skills from the module class. The highest percentage of aspect was rebuttal aspect (27.27%) followed by evidence 26,06% and reasoning 23.94%, while the aspect of claim increased by 20.61%. The independent t-test results showed that there was a significant difference between pre-test and post-test results of the module class. It can be concluded that the ecosystem module with problem-based learning material was effective to improve students’ scientific argumentation skills. The product of this reasearch can be use as a tools to improve students’ scientific argumentation skills.

Rebuttal is an essential aspect in scientific argumentation skill. Level of scientific argumentation skill depends on the quality of the rebuttal process. Students who can produce a high-quality rebuttal to defend their claims are proved higher level of scientific argumentation skill than the student who can only produce claims, evidence and reasoning. Problem-based learning (PBL) is a learning model that provides real life ill-structured problem, that need to be solved through investigation and discussion. It is able to help students to enhance their rebuttal skill. This research was aimed to analyze the rebuttal improvement process by applying PBL based module in 10th-grade student of SMAN 1 Punung. This research was an evaluation stage from our R&D research using pretest-post test control-experiment group design. Data were collected using test, interview, and classroom observation. The result showed that the student's rebuttals in the experimental group increase up to 27,27%. The t-test result also indicated different significant result between pretest and posttest scores. Based on the research result can be concluded, that by implementing PBL based model in the10th-grade senior high school is able to improve student's rebuttal skill.