This study is descriptive qualitative research employing a case study approach, focusing on the implementation of Indonesian language teaching under the Kurikulum Merdeka at SMA Negeri 1 Widodaren. The sampling technique used was purposive sampling. Data were collected through participatory observation, in-depth interviews, and document analysis. Data validity was tested using source triangulation. The findings reveal that the lesson planning procedures implemented by the teacher did not fully align with the guidelines set by the Ministry of Education, Culture, Research, and Technology (Kemendikbudristek) in 2024. Although the teacher followed the stages of (a) analyzing learning outcomes, (b) formulating learning objectives and learning trajectories, and (c) planning instruction and assessment, these steps were not carried out in accordance with the prescribed guidelines. The implementation of the learning process did not reflect the prepared teaching module, particularly in terms of instructional steps, methods, media, and assessment. The inconsistencies were evident in the lack of assessment at the beginning, during, and after the learning process; failure to meet students’ needs; unclear learning priorities; and insufficient reflection. Challenges encountered included adaptation to the Kurikulum Merdeka, selection of learning models and teaching resources, and assessment systems. Proposed solutions include fostering adaptability through acceptance of change, experimentation with new methods, continuous professional development, implementation of recommended instructional models, and alignment with the Kurikulum Merdeka assessment system.

Penelitian ini merupakan penelitian deskriptif kualitatif dengan pendekatan studi kasus yang berfokus pada penerapan pembelajaran Bahasa Indonesia dalam Kurikulum Merdeka di SMA Negeri 1 Widodaren. Teknik pengambilan sampel dilakukan dengan purposive sampling. Pengumpulan data dilakukan melalui observasi partisipatif, wawancara mendalam, dan analisis dokumen. Validitas data diuji menggunakan metode triangulasi sumber. Hasil penelitian menunjukkan bahwa prosedur perencanaan pembelajaran yang dilaksanakan guru tidak sepenuhnya sesuai dengan pedoman yang ditetapkan oleh Kemendikbudristek tahun 2024. Guru melakukan perencanaan dengan tahapan (a) analisis capaian pembelajaran, (b) menyusun tujuan pembelajaran dan alur pembelajaran, dan (c) merencanakan pembelajaran dan asesmen yang belum sesuai dengan arahan pedoman. Pelaksanaan pembelajaran belum sesuai dengan modul ajar yang direncanakan, termasuk dalam langkah kegiatan, metode, media, dan penilaian. Ketidaksesuaian tampak pada karakteristik yang belum memanfaatkan asesmen pada awal, proses, dan akhir, kebutuhan peserta didik, prioritas kemajuan belajar, serta refleksi. Kendala yang dihadapi mencakup adaptasi terhadap Kurikulum Merdeka, model pembelajaran dan sumber ajar Kurikulum Merdeka, dan ssstem penilaian atau asesmen Kurikulum Merdeka. Solusi yang dapat ditawarkan berupa adaptasi penerapan dengan menerima perubahan, bereksperimen dengan metode baru serta terus belajar, menerapkan model pembelajaran yang disarankan Kurikulum Merdeka, menyesuaikan dengan sistem asesmen Kurikulum Merdeka.