<![CDATA[ABSTRAK  Tujuan penelitian untuk membekalkan keterampilan menulis bahan ajar IPA berbasis STREM-R menggunakan Triple Step Writing Strategy (TS-WS) secara daring beserta kendala-kendala selama pembelajaran. Strategi TS-WS meliputi perencanaan, translasi, dan revisi. Sample mahasiswa calon guru berjumlah 26 orang menggunakan satu kelas. The One Group Pre-Test & Post-Test Design. Penugasan menulis bahan ajar awal (O1) selanjutnya dilakukan perlakuan TS-WS dan merevisi tulisan bahan ajar/bahan ajar akhir (O2). Pengukuran keterampilan menulis menggunakan instrumen skoring dan rubric asesmen kinerja. Analisis data menggunakan normalized gain (n-gain,) perhitungan persentase pada kriteria tertentu dan uji statistik wilcoxon. Instrumen kendala pembelajaran menggunakan angket pertanyaan terstruktur dan catatan lapangan yang dianalisis secara deskriptif kualitatif. Hasil n-gain bahan ajar secara umum menunjukkan 32% berkriteria sedang dan 44% berkriteria rendah. Uji wilcoxon menunjukkan terdapat perbedaan signifikan antara tulisan bahan ajar awal dan tulisan bahan ajar akhir. Kendala-kendala, antara lain: kesulitan membuat indikator pencapaian kompetensi, menganalisis dimensi pengetahuan, menerapkan STEM-R pada konten materi IPA, dan kondisi pembelajaran daring. Strategi TS-WS dapat membekalkan keterampilan menulis bahan Ajar IPA STEM-R pada sebagian besar mahasiswa calon guru  Kata  kunci— Bahan Ajar IPA, STEM-R, Triple Step Writing Strategy  ABSTRACT  The purpose of this research is to improve the skill in writing science-based STREM-R teaching materials using the Triple Step Writing Strategy (TS-WS) online, along with finding out the challenges encountered during the learning process. The TS-WS strategy includes planning, translation, & revision. The sample consists of 26 pre-service teachers in one class. The research uses the One Group Pre-Test & Post-Test Design. Assignments given were writing initial teaching materials (O1) followed by TS-WS treatment and revising the teaching materials/final teaching materials (O2). Writing skill assessment was done using a scoring instrument & performance assessment rubric. Data were analyzed using normalized gain (n-Gain), percentage calculations for certain criteria, & Wilcoxon statistical test. The learning challenges instrument used was a structured questionnaire & field notes were analyzed descriptive-qualitatively. The overall n-Gain of the teaching materials showed 32% to be "moderate" & 44% to be "low". The Wilcoxon test showed a significant difference between the writings of initial and final teaching materials. Some of the challenges encountered are difficulties in creating performance indicators, analyzing knowledge dimensions, applying STEM-R to science content and online learning conditions. The TS-WS strategy can provide improve the pre-service teacher's skills in writing science-based STEM-R teaching materials. Keywords— Science Teaching Materials, STEM-R, Triple Step Writing Strategy]]>
