Penelitian dilaksanakan berdasarkan hasil pengamatan yang kemudian ditemukan bahwa tanggung jawab siswa kelas VIII A dalam pembelajaran masih rendah. Saat pembelajaran berlangsung terdapat siswa yang terlambat memasuki kelas, tidak membawa peralatan belajar dengan lengkap, tidak mengerjakan tugas yang diberikan, dan tidak memberikan fokus saat pembelajaran berlangsung. Oleh karena itu, peneliti memutuskan untuk menerapkan reward marble jar. Melalui penerapan reward marble jar diharapkan dapat meningkatkan tanggung jawab siswa dalam pembelajaran. Tujuan penelitian ini adalah untuk mengetahui apakah penerapan reward marble jar dapat meningkatkan tanggung jawab siswa dan menjelaskan langkah-langkah penerapan reward marble jar. Metode penelitian ini menggunakan penelitian tindakan kelas (PTK) yang dikemukakan oleh Robert P. Pelton. Penelitian dilaksanakan dalam empat penerapan tindakan, mulai dari 11 Oktober 2018 – 19 Oktober 2018 dengan subjek penelitian sebanyak 6 siswa kelas VIII A di Sekolah Palembang Harapan. Data penelitian diperoleh melalui lembar kuisioner guru subjek, jurnal refleksi peneliti, lembar checklist siswa, lembar observasi mentor, umpan balik, dan lembar checklist mentor. Hasil penelitian menunjukkan bahwa siswa mampu meningkatkan tanggung jawab pada indikator 1 sebesar 70,67%, indikator 2 sebesar 84,80%, indikator 3 sebesar 92,18%, dan indikator 4 sebesar 94,64% dengan melaksanakan keseluruhan tahapan reward marble jar selama empat kali penerapan tindakan. Maka disimpulkan bahwa penerapan reward marble jar dapat meningkatkan tanggung jawab siswa kelas VIII A di Sekolah Palembang Harapan./ This research was conducted based on observation. It was found that responsibility of grade VIII A students in the classroom was low. During the teaching and learning activity, there were students who were late to enter the classroom, did not bring complete learning equipment, did not do task that given given by teacher, and could not focus to the lesson. Therefore, the researcher decided to implement marble jar reward. The aim of this research was to know whether the implementation of marble jar reward could enhance students’ responsiblity and to explain the steps of marble jar reward implementation. Research method that used was Classroom Action Research (CAR) by Robert P. Pelton. The research was conducted in four action implementation, started from 11th of October 2018 until 19th of October 2018 with 6 students of VIII A in Sekolah Palembang Harapan as research subject. Data of the research was gotten by researcher through subject teacher questionnaire sheet, researcher journal reflection, student’s checklist sheet, mentor observation sheet, and mentor checklist sheet. The result of this research showed that students able to enhance their responsibility, 70.6% in indicator 1, indicator 2 was 84.80%, indicator 3 was 92.18%, and indicator 4 was 94.64% by doing all of the steps of marble jar reward in four action implementation. So, it could be concluded that the implementation of marble jar reward could enhance students’ responsibility of VIII A in Sekolah Palembang Harapan.