<![CDATA[21st-century education demands mastery of the 4C skills to face global challenges through innovative learning models. This study focuses on analyzing the effectiveness of the Cooperative Project Based Learning model in improving 4C competencies and student learning outcomes based on group formation patterns. This quasi-experimental study with a non-equivalent control group design was conducted at MTsN 3 Kediri City in January 2026. Researchers involved two experimental classes to compare the method of recruiting group members independently by students versus groups determined directly by the teacher. The research stages included a pretest, implementation of the excretory organ miniature project, presentation, and final evaluation through a posttest and 4C questionnaire. Data were analyzed using non-parametric tests assisted by SPSS because they were not normally distributed. The results of the Mann-Whitney test showed no significant differences between groups in the pretest (p = 0.970), posttest (p = 0.947), or 4C scores (p = 0.964). However, the Wilcoxon test proved a significant increase in both classes with a p value of 0.001. The main conclusion states that the CPjBL model is very effective in improving academic achievement and 4C competencies, although the group formation mechanism does not have a significant impact on this effectiveness. Teachers are advised to continue using this collaborative model to optimize the potential for social interaction, creativity, communication, collaboration, and critical reasoning of all students in a deep, holistic, transparent, accurate, objective, systematic, comprehensive, consistent, educational, and effective manner. ABSTRAK Pendidikan abad ke-21 menuntut penguasaan keterampilan 4C guna menghadapi tantangan global melalui model pembelajaran inovatif. Penelitian ini berfokus pada analisis efektivitas model Cooperative Project Based Learning dalam meningkatkan kompetensi 4C dan hasil belajar siswa berdasarkan pola pembentukan kelompok. Studi kuasi eksperimen dengan desain non-equivalent control group ini dilaksanakan di MTsN 3 Kota Kediri pada Januari 2026. Peneliti melibatkan dua kelas eksperimen guna membandingkan metode perekrutan anggota kelompok secara mandiri oleh siswa melawan kelompok yang ditentukan langsung oleh guru. Tahapan penelitian meliputi pretest, pelaksanaan proyek pembuatan miniatur organ ekskresi, presentasi, serta evaluasi akhir melalui posttest dan angket 4C. Data dianalisis menggunakan uji non-parametrik berbantuan SPSS karena tidak berdistribusi normal. Hasil uji Mann-Whitney menunjukkan tidak ada perbedaan signifikan antar kelompok pada nilai pretest (p=0,970), posttest (p=0,947), maupun skor 4C (p=0,964). Namun, uji Wilcoxon membuktikan adanya peningkatan signifikan pada kedua kelas dengan nilai p=0,001. Simpulan utama menyatakan bahwa model CPjBL sangat efektif meningkatkan capaian akademis dan kompetensi 4C, meskipun mekanisme pembentukan kelompok tidak memberikan pengaruh yang berarti terhadap efektivitas tersebut. Guru disarankan tetap menggunakan model kolaboratif ini untuk mengoptimalkan potensi interaksi sosial, kreativitas, komunikasi, kolaborasi, serta nalar kritis seluruh siswa secara mendalam, holistik, transparan, akurat, objektif, sistematis, menyeluruh, konsisten, edukatif, dan berdaya guna. ]]>
