This study aims to find out about the results of the development of discussion textual writing teaching material based on the finding in the seventh grade students of SMP Negeri 4 Medan. The research method used is research and development research and development (R & D) proposed by Vienna Sanjaya refers to Borg & Gall model. The trial subjects consisted of 3 students with individual trials, 9 students with small group trials, and 32 students with limited field trials. Technique of data collection used observation, interviews, questionnaires, and test of writing text. The results showed that: (1) material expert validation includes content feasibility with an average of 89.84% on very good criteria, presentation feasibility with an average of 88.46% on very good criteria, and language assessment with an average of 90.38% on very good criteria, (2) validation of design experts with an average of 92.08% on very good criteria, (3) teacher response with an average of 89.17% on very good criteria, (4) individual testing with an average of 76.39% on good criteria, (5) small group trials with an average of 81.94% on very good criteria, and (6) limited field tests with an average of 92.77% on very good criteria. The result of discussion textual writing test before using the module is 70,87%, while the result of the test of writing discussion text of the student after using the module increased by 80,09%. The difference is 9.22%. from before to after using the module. This proves that teaching materials to write discussion texts developed can improve student learning outcomes by using discovery-based learning.
Keywords: Development, Discovery-Based Learning, Discussion Texts, Teaching Materials
