<![CDATA[Writing skills are essential basic competencies that must be mastered by elementary school students as a means of expressing ideas, but in reality the quality of students' writing is still very low due to the many errors in the application of language rules. The focus of the problem in this study is directed at the analysis of language errors that include aspects of spelling, syntax, morphology, and word choice in grade IV students of SD Inpres Sikam, East Nusa Tenggara. The important steps or stages of this study use the Classroom Action Research approach which is implemented through two systematic cycles, including the planning stage, implementation of actions with structured exercises, process observation, and critical reflection. Based on the findings of the research, quantitative data shows a significant downward trend in the number of language errors by 31%, from a total of 198 errors in cycle I to 157 errors in cycle II. In detail, a significant decrease is seen in the morphology aspect by 57%, word choice by 46%, neatness of writing by 37%, syntax by 34%, and spelling by 18%. These findings prove that identifying dominant error patterns makes it easier for teachers to provide targeted corrective feedback to students. The main conclusion confirms that the application of classroom action research through error analysis is very effective in improving the understanding of language rules and increasing the quality of students' writing skills in a sustainable manner through dynamic instructional improvements. ABSTRAK Keterampilan menulis merupakan kompetensi dasar esensial yang harus dikuasai siswa sekolah dasar sebagai sarana ekspresi gagasan, namun pada kenyataannya kualitas tulisan siswa masih sangat rendah akibat banyaknya kesalahan penerapan kaidah bahasa. Fokus masalah dalam penelitian ini diarahkan pada analisis kesalahan berbahasa yang mencakup aspek ejaan, sintaksis, morfologi, hingga pilihan kata pada siswa kelas IV SD Inpres Sikam, Nusa Tenggara Timur. Langkah atau tahapan penting penelitian ini menggunakan pendekatan Penelitian Tindakan Kelas yang dilaksanakan melalui dua siklus sistematis, meliputi tahap perencanaan, pelaksanaan tindakan dengan pemberian latihan terstruktur, observasi proses, serta refleksi kritis. Berdasarkan temuan hasil penelitian, data kuantitatif menunjukkan adanya tren penurunan jumlah kesalahan berbahasa secara signifikan sebesar 31 %, dari total 198 kesalahan pada siklus I menjadi 157 kesalahan pada siklus II. Secara terperinci, penurunan signifikan terlihat pada aspek morfologi sebesar 57 %, pilihan kata 46 %, kerapian tulisan 37 %, sintaksis 34 %, serta aspek ejaan 18 %. Temuan ini membuktikan bahwa identifikasi pola kesalahan yang dominan memudahkan guru dalam memberikan umpan balik korektif yang tepat sasaran bagi siswa. Simpulan utama menegaskan bahwa penerapan penelitian tindakan kelas melalui analisis kesalahan sangat efektif dalam memperbaiki pemahaman kaidah bahasa serta meningkatkan kualitas keterampilan menulis siswa secara berkelanjutan melalui perbaikan instruksional yang dinamis. ]]>
