Berdasarkan observasi yang dilakukan oleh peneliti pada saat melaksanakan kegiatan belajar mengajar, ditemukan siswa tidak aktif dalam memberikan pertanyaan dan pendapat, hal tersebut nampak dalam diskusi dan penyelesaian masalah dalam kelompok, serta dijumpai siswa tidak memerhatikan saat peneliti memberikan penjelasan materi. Maka dari itu, penelitian ini bertujuan untuk meningkatkan keaktifan belajar siswa dalam kegiatan belajar mengajar dengan menggunakan metode TPS (think pair share). Jenis penelitian yang digunakan adalah Penelitian Tindakan Kelas (PTK). Penelitian ini dilakukan pada tanggal 24 Agustus sampai 24 Oktober 2018 di SMP Kristen Indonesia, Magelang dengan metode TPS (think pair share) yang diterapkan sebanyak tiga kali penerapan dengan melibatkan delapan siswa. Instrumen penelitian yang digunakan adalah RPP, lembar observasi mentor (checklist) dan deskriptif, jurnal refleksi, dan wawancara mentor. Hasil dari penelitian ini bahwa penerapan metode TPS (think pair share) dapat meningkatkan keaktifan belajar siswa di kelas. Di mana metode TPS (think pair share) ini telah dilaksanakan dengan baik oleh peneliti dan hasil setiap penerapannya adalah 100 %./ In accordance with the researcher’s observation, the researcher found some students who were not active during the teaching and learning process. The students were not active asking question and giving an opinion. The students were not actively involved in a group’s discussion and problem-solving. The students also did not pay attention when the researcher explained the lesson. Therefore, the purpose of this research was to increase students’ active learning during teaching and learning process through the implementation of Think Pair Share (TPS) Method. The research method used by the researcher was Classroom Action Research (CAR). This research was conducted on August 24, 2018 until October 24, 2018 in SMP Kristen Indonesia, Magelang. Think Pair Share (TPS) Method was implemented three times and it involved eight students. The instruments used by the researcher were lesson plan, mentor observation sheet (checklist), reflection journal, and mentor interview. The result of this research was the implementation of Think Pair Share (TPS) Method can increase students’ active learning in the classroom, being active during the teaching and learning process already become students’ habit. The Think Pair Share (TPS) Method was well implemented by the researcher, the result of each implementation was 100%.