<![CDATA[Partnership for 21st century learning (P21) requires students to have life and career skills, learning and innovation skills, and information media and technology skills. The curriculum of 2013 is related todemands of 21st century learning, namely the ability to think critically, communicate, collaborate and to be creative. The strategy can be used to achieve these demands is to train students with scientificargumentation. The ability of arguing students must be able to understand the evidence used to relate the theory, and assess the feasibility between data and arguments. One method that can be used to practice scientific argumentation is debate. Therefore, this study was developed a debate-based worksheet with components that include four main stages, namely constructive speech I, constructive speech II, crossexamination, and conclusion. The assessment of scientific argumentation refers to Toulmin's Argument Pattern (TAP). This study aimed to describe the validity of debate-based worksheets to train students’ scientific argumentation skills on the evolution subject, sub-material the origin of living things and theory of evolution based on the results of validation by experts. This research was development of Fenrich Instructional Cycle model which include several phases consists of (analysis, planning, design, development, implementation, evaluation, and revision) with modification without the implementation phase due to the Covid-19 pandemic condition. The results of the study showed that the validity of debatebased worksheets to train scientific argumentation skills was very valid. The average score of validation was 3.72 based on the feasibility of presentation, content, language, characteristics of the worksheet to train science argumentation skills and characteristics of debate-oriented worksheet. Thus, this research will be used as the basic for further research on the practicality and effectiveness of worksheet to train students’ scientific argumentation skills.Keywords: worksheet, debate, scientific argumentation, evolution.]]>
