<![CDATA[ABSTRAK Penelitian ini bertujuan untuk menganalisis peningkatan keaktifan dan hasil belajar mahasiswa pada materi kimia air melalui penerapan model pembelajaran kooperatif Two Stay Two Stray (TSTS). Latar belakang penelitian ini adalah rendahnya tingkat keaktifan dan hasil belajar mahasiswa dalam mata kuliah kimia air yang seringkali diajarkan secara konvensional, sehingga kurang mendorong interaksi dan pemahaman mendalam. Penelitian ini menggunakan pendekatan kuantitatif dengan desain Quasi-Eksperimen jenis Nonequivalent Control Group Design. Populasi penelitian adalah mahasiswa program studi Pendidikan IPA yang mengambil mata kuliah Kimia Lingkungan. Sampel dipilih secara purposive sampling, terdiri dari dua kelas: satu kelas eksperimen yang menerapkan model TSTS, dan satu kelas kontrol yang menggunakan metode pembelajaran konvensional. Data keaktifan dikumpulkan melalui lembar observasi, sedangkan data hasil belajar diperoleh dari pretest dan posttest yang diberikan kepada kedua kelompok. Analisis data dilakukan secara deskriptif dan inferensial. Data hasil belajar dianalisis menggunakan Independent Sample T-Test atau Mann-Whitney U Test setelah uji normalitas dan homogenitas, serta perhitungan N-Gain untuk melihat peningkatan. Data keaktifan dianalisis secara deskriptif persentase. Hasil penelitian menunjukkan bahwa model pembelajaran Two Stay Two Stray secara signifikan mampu meningkatkan keaktifan dan hasil belajar mahasiswa pada materi Kimia Air dibandingkan dengan metode pembelajaran konvensional. Nilai N-gain Score pada tabel pada kelas eksperimen berada dalam kategori tinggi yaitu 0,74 berada pada 0,30 > N-gain > 0,70, sedangkan pada kelas kontrol mendapatkan nilai 0,68 berada pada 0,30 ≤ N-gain ≤ 0,70 berada dalam kategori sedang. Peningkatan keaktifan terlihat dari partisipasi aktif mahasiswa dalam diskusi kelompok dan berbagi informasi, yang berkolerasi positif dengan peningkatan pemahaman konsep. Kata kunci : Two Stay Two Stray (TSTS), Kimia Air, Keaktifan Mahasiswa, Hasil Belajar ABSTRACT This study aims to analyze the increase in student activity and learning outcomes in water chemistry materials through the application of the Two Stay Two Stray (TSTS) cooperative learning model. The background of this research is the low level of student activity and learning outcomes in water chemistry courses which are often taught conventionally, so that they do not encourage interaction and deep understanding. This study uses a quantitative approach with a Quasi-Experimental design of the Nonequivalent Control Group Design. The research population is students of the Sains study program who take the Environment Chemistry course. The sample was selected by purposive sampling, consisting of two classes: one experimental class applying the TSTS model, and one control class using conventional learning methods. Activity data was collected through observation sheets, while learning outcome data was obtained from pretest and posttest given to both groups. Data analysis was carried out descriptively and inferentially. The learning outcome data was analyzed using the Independent Sample T-Test or Man-Whitney U Test after the normality and homogeneity test, as well as the calculation of N-Gain to see improvement. Activeness data was analyzed descriptively as a percentage. The results of the study show that the Two Stay Two Stray learning model is significantly able to increase student activity and learning outcomes in Water Chemistry materials compared to conventional learning methods. The N-gain Score value in the table in the experimental class was in the high category, which was 0.74, was in the high category, which was 0.30 > N-gain > 0.70, while in the control class, the value of 0.68 was in the 0.30 ≤ N-gain ≤ 0.70 was in the medium category. The increase in activeness can be seen from the active participation of students in group discussions and information sharing, which is positively correlated with increased understanding of concepts. Keywords : Two Stay Two Stray (TSTS), Water Chemistry, Student Activity, Learning Outcomes]]>
