Abstrak
Tujuan dari penelitian ini adalah untuk meningkatkan: (1) minat belajar siswa, (2) kemampuan berpikir kritis siswa, dan (3) prestasi belajar siswa pada materi hidrolisis garam melalui model problem based learning (PBL) berbantuan modul.
Penelitian ini merupakan Penelitian Tindakan Kelas (Classroom Action Research) yang dilaksanakan dalam dua siklus. Tiap siklus terdiri dari tahap perencanaan, pelaksanaan, observasi dan refleksi. Teknik sampling penelitian ialah non probability sampling dengan subjek siswa kelas XI  IPA 2 SMA Negeri 2 Surakarta. Teknik pengumpulan data adalah dengan wawancara, lembar observasi, angket dan tes. Teknik analisis data ialah dengan pendekatan deskriptif kualitatif dan teknik uji validitas data yang diterapkan ialah triangulasi data.
Hasil penelitian menunjukkan bahwa model Problem Based Learning (PBL) berbantuan modul pada materi hidrolisis garam dapat meningkatkan: (1) minat belajar siswa, dengan peranan guru dalam memberikan pelayanan yang maksimal antusias siswa dalam proses pembelajaran terus meningkat tiap pertemuannya, dibuktikan dengan capaian ketuntasan siklus I sebesar 80,00%, (2) kemampuan berpikir kritis siswa, dengan siswa dibimbing untuk membangun pengetahuannya sendiri, tingkat analisis penalaran siswa semakin baik, dibuktikan dengan capaian ketuntasan siklus I 46,67% dan meningkat menjadi 76,67% pada siklus II, dan (3) prestasi belajar siswa, karena dalam pembelajaran juga menekankan dan mengajarkan nilai yang baik dari guru terhadap siswa agar memiliki kepribadian baik maka ketuntasan aspek sikap pada siklus I sebesar 90,00%. Selanjutnya sebelum kegiatan praktikum berlangsung guru memberikan pengarahan terperinci mengenai prosedur kerja agar siswa tidak banyak melakukan kesalahan dan bekerja dengan baik dan benar, sehingga ketuntasan aspek keterampilan pada siklus I sebesar 86,67%. Kemudian pada aspek pengetahuan kemampuan pemahaman siswa meningkat karena siswa selalu aktif menyelesaikan soal latihan dan kegiatan yang diberikan oleh guru yang dibuktikan dengan capaian ketuntasan aspek pengetahuan siklus I 40,00% dan meningkat menjadi 76,67% pada siklus II. 
Kata Kunci: Problem Based Learning, Modul, Minat Belajar, Kemampuan  Berpikir Kritis, Prestasi Belajar
Abstract
This research aims  to increase: (1) students’ learning interests, (2) students’ critical thinking skills, and (3) students’ learning achievement on salt hydrolysis subject by implementing Problem Based Learning (PBL) assisted with modules.
This research is a Classroom Action Research which has two cycles in which in each cycle consists of several steps: planning, implementation, observation, and reflection. The sampling technique was non probability sampling and the subject was class XI IPA 2 SMA Negeri 2 Surakarta. The data collection techniques used were interviews, observation sheets, questionnaire and tests. The data were analyzed by descriptive qualitative approach and the data validity technique applied was triangulation method.
The results of this research show that (1) the students’ learning interests, with the teachers’ role in providing maximum guidance, students’ enthusiasm in the learning process was continues to increased each meeting, as evidenced in the first cycle completeness reached 80.00%, (2) the students’ critical thinking skills, students were guided to build their own knowledge, therefore the level of analyzed skill of students' reasoning was better. As evidenced in the first cycle completeness reached 46.67%, then was increasing in the second cycle attained 76.67%, and (3) the students’ learning achievement, because in learning processed teacher also emphasized and teached good attitude so that students have a good personality. Thus, the completeness of the attitude aspects was obtained in the first cycle 90.00%. Furthermore, before laboratory work activities took place the teacher gives detailed directions on work procedures so that students didn’t made many mistakes and work well and correctly, so that the completeness of the aspects of skills in the first cycle reached 86.67%. Then in the aspect of knowledge, the ability of students' understanding increased because students were always actively completing the practiced questions and activities provided by the teacher, as evidenced in the first cycle completeness reached 40.00% and increased attained 76.67% in the second cycle.
Keyword: Problem Based Learning, Modules, Interest in Learning, Critical Thinking Skills, Learning Achievement