<![CDATA[Pemahaman konsep matematika merupakan komponen penting dalam pembelajaran Sistem Persamaan Linear Dua Variabel (SPLDV) karena berperan dalam kemampuan siswa memecahkan masalah kontekstual. Penelitian ini bertujuan untuk menganalisis pemahaman konsep siswa berdasarkan teori APOS (Action, Process, Object, Schema) yang menguraikan tahapan berpikir matematis siswa. Studi ini menggunakan pendekatan kualitatif dengan teknik pengumpulan data melalui tes diagnostik dan wawancara mendalam terhadap tiga siswa yang mewakili kategori kemampuan tinggi, sedang, dan rendah dari total 28 siswa yang mengikuti tes. Hasil menunjukkan bahwa siswa berkemampuan tinggi mampu menyelesaikan soal SPLDV secara hampir menyeluruh berdasarkan tahapan APOS, meskipun terdapat kekurangan dalam representasi tertulis. Siswa berkemampuan sedang menunjukkan pemahaman terbatas, khususnya dalam menentukan metode penyelesaian dan menarik kesimpulan. Sementara itu, siswa berkemampuan rendah hanya menunjukkan pemahaman semu, karena jawaban diperoleh dari sumber eksternal tanpa melalui proses konstruksi pengetahuan. Temuan ini menegaskan efektivitas teori APOS sebagai kerangka analisis untuk mengidentifikasi kesulitan belajar matematika secara komprehensif. Penelitian ini memberikan kontribusi pada pengembangan strategi pembelajaran berbasis tahapan kognitif siswa dan menyarankan eksplorasi lanjutan dengan integrasi pendekatan teknologi. Kata kunci: pemahaman konsep matematika; teori APOS; SPLDV; pembelajaran kontekstual; kemampuan berpikir matematis Abstract: Conceptual understanding in mathematics is a critical component in learning Systems of Linear Equations in Two Variables (SPLDV), as it plays a significant role in students’ ability to solve contextual problems. This study aims to analyze students' conceptual understanding based on the APOS theory (Action, Process, Object, Schema), which outlines the stages of mathematical thinking. A qualitative approach was employed, involving diagnostic tests and in-depth interviews with three students representing high, moderate, and low ability levels, selectsed from a total of 28 students who participated in the test. The results revealed that the high-ability student was able to complete the SPLDV problems across nearly all APOS stages, although with some limitations in written representation. The moderate-ability student demonstrated partial understanding, especially in selecting problem-solving methods and drawing conclusions. Meanwhile, the low-ability student showed only surface-level understanding, as responses were obtained from external sources without internal knowledge construction. These findings affirm the effectiveness of the APOS theory as an analytical framework to identify learning difficulties in mathematics comprehensively. This research contributes to the development of instructional strategies based on students’ cognitive stages and suggests further exploration of the integration of technological approaches. Keywords: mathematics conceptual understanding; APOS theory; systems of linear equations; contextual learning; mathematical thinking skills]]>
