<![CDATA[ABSTRACT Mathematical problem-solving ability among junior high school students in contextual topics such as profit and loss remains low because learning practices have not fully connected mathematical concepts with real-life situations, and the implementation of STEM integrated Project Based Learning (PjBL-STEM) is still limited. This study aims to describe students’ profiles of mathematical problem-solving abilities through STEM integrated Project Based Learning (PjBL-STEM) on profit and loss material through a natural compost making project. This study employed a qualitative approach using a case study design. The research subjects were students of class VIII B at SMP Negeri 1 Gading, who were purposively selected and grouped into three ability categories: high, medium, and low. Data were collected through problem-solving skill tests, observations, semi-structured interviews, and documentation. Data analysis used the interactive model of Matthew B. Miles and A. Michael Huberman, which included data reduction, data presentation, and conclusion drawing, referring to George Polya’s problem-solving steps. The results showed that students’ mathematical problem-solving abilities were categorized into high (15.38%), medium (57.69%), and low (26.92%), with the majority of students in the medium category. The implementation of PjBL-STEM provided meaningful learning experiences; however, students’ problem-solving abilities still varied across categories. The implementation of PjBL-STEM through the natural compost making project offered significant and relevant learning experiences, although students’ problem-solving skills had not yet developed evenly. ABSTRAK Kemampuan pemecahan masalah matematis siswa SMP pada materi kontekstual seperti untung-rugi masih rendah karena pembelajaran belum sepenuhnya mengaitkan konsep matematika dengan situasi nyata dan penerapan PjBL-STEM masih terbatas. Penelitian ini bertujuan menggambarkan profil kemampuan pemecahan masalah matematis siswa melalui pembelajaran Project Based Learning terintegrasi STEM (PjBL-STEM) pada materi untung-rugi melalui proyek pembuatan kompos alami. Studi ini menerapkan pendekatan kualitatif melalui desain studi kasus. Subjek penelitian adalah siswa kelas VIII B di SMP Negeri 1 Gading yang dipilih secara sengaja dan dikelompokkan ke dalam tiga kategori kemampuan: tinggi, sedang, dan rendah. Data diperoleh melalui tes keterampilan pemecahan masalah, pengamatan, wawancara semi-terstruktur, dan dokumentasi. Analisis data dengan model interaktif dari Matthew B. Miles dan A. Michael Huberman yang mencakup reduksi data, presentasi data, dan penarikan kesimpulan, merujuk pada langkah-langkah pemecahan masalah menurut George Polya. Hasil penelitian menunjukkan bahwa kemampuan pemecahan masalah matematis siswa terbagi dalam kategori tinggi (15,38%), sedang (57,69%), dan rendah (26,92%), dengan mayoritas siswa berada pada kategori sedang. Implementasi PjBL-STEM memberikan pengalaman belajar yang bermakna, namun kemampuan pemecahan masalah siswa masih menunjukkan variasi pada setiap kategori. Implementasi PjBL-STEM melalui proyek pembuatan kompos alami memberikan pengalaman belajar yang signifikan dan relevan, namun keterampilan pemecahan masalah siswa masih belum berkembang secara merata.]]>
