<![CDATA[The ability to systematically compose scientific writing is an important academic skill, yet many students still struggle to fully understand its structure, highlighting the need for learning media that can guide students through this structure in a gradual manner. This study aims to improve students' understanding of scientific writing structure through the use of Student Worksheets (LKPD) among eleventh-grade students of class XI F at SMA Muhammadiyah 3 Jember. The study employed a Classroom Action Research (CAR) method based on the Kemmis and McTaggart model, consisting of planning, action, observation, and reflection across two cycles, conducted on 4 May 2026 (pretest), 6 May 2026 (Cycle I), and 11 May 2026 (Cycle II), involving 32 students as subjects. Data were collected through tests and observations, then analyzed using descriptive quantitative methods. The key findings revealed a significant improvement in students' understanding, with learning mastery increasing from 31.25% (pretest) to 84.38% (Cycle II), supported by refinements to the LKPD and the implementation of scaffolding, alongside increased student engagement and motivation. These findings indicate that scaffolding-based LKPD is effective in enhancing students' understanding of scientific writing structure. ABSTRAK Kemampuan menyusun karya tulis ilmiah secara sistematis merupakan keterampilan akademik penting yang masih sulit dikuasai oleh banyak siswa, sehingga diperlukan media pembelajaran yang membimbing pemahaman struktur tersebut secara bertahap. Penelitian ini bertujuan meningkatkan pemahaman struktur karya tulis ilmiah melalui Lembar Kerja Peserta Didik (LKPD) pada siswa kelas XI F SMA Muhammadiyah 3 Jember. Penelitian menggunakan metode Penelitian Tindakan Kelas (PTK) model Kemmis dan McTaggart yang terdiri atas perencanaan, tindakan, observasi, dan refleksi dalam dua siklus, dilaksanakan pada 4 Mei 2026 (pretest), 6 Mei 2026 (Siklus I), dan 11 Mei 2026 (Siklus II) dengan subjek 32 siswa. Data diperoleh melalui tes dan observasi, dianalisis secara deskriptif kuantitatif. Temuan utama menunjukkan peningkatan signifikan pemahaman siswa, dengan ketuntasan belajar meningkat dari 31,25% (pretest) menjadi 84,38% (Siklus II), didukung oleh perbaikan LKPD dan penerapan scaffolding, serta peningkatan keterlibatan dan motivasi siswa. Dengan demikian, LKPD berbasis scaffolding terbukti efektif meningkatkan pemahaman struktur karya tulis ilmiah siswa.]]>
