ABSTRAK
Penelitian ini bertujuan untuk meningkatkan prestasi belajar dan kemampuan berpikir kritis siswa melalui penerapan model pembelajaran PBL (Problem Based Learning) di kelas XI IPA 2 SMA Negeri 1 Gondang Tahun Pelajaran 2014/2015 pada materi pokok kelarutan dan hasil kali kelarutan.
Penelitian ini merupakan Penelitian Tindakan Kelas (Classroom Action Research) dengan model Kurt Lewin yang dilaksanakan dalam dua siklus. Setiap siklus diawali tahap persiapan kemudian dilanjutkan tahap pelaksanaan siklus yang terdiri dari perencanaan tindakan, pelaksanaan tindakan, observasi dan evaluasi, serta refleksi. Subjek penelitian adalah siswa kelas XI IPA2 SMA Negeri 1 Gondang  sebanyak 32 siswa dengan penelitian dikhususkan  pada materi pokok Kelarutan dan Hasil Kali Kelarutan. Data diperoleh melalui pengamatan, wawancara dengan guru, ulangan harian, angket dan kajian dokumen. Teknik analisis data yang digunakan adalah teknik kualitatif didukung data kuantitatif.
Berdasarkan hasil penelitian, dapat disimpulkan bahwa(1) Penerapanpendekatan pembelajaran konstruktivisme melalui model PBL (Problem Based Learning)dapat meningkatkan kemampuan berpikir kritis siswa pada materi Kelarutan dan Hasil Kali Kelarutan di kelas XI IPA 2 SMA Negeri 1 Gondang.Pada aspek berpikir kritis, siklus I menunjukkan siswa yang memiliki kemampuan berpikir kritis dengan kategori tinggi 31,25%, sedang 31,25% dan rendah 37,5%. Sedangkan pada siklus 2, siswa yang memiliki kemampuan berpikir kritis dengan kategori tinggi 68,75%, sedang 25% dan rendah 6,25%. (2) Penerapan pendekatan pembelajaran konstruktivisme melalui PBL (Problem Based Learning)dapat meningkatkan kemampuan prestasi belajar siswa pada materi Kelarutan dan Hasil Kali Kelarutan di kelas XI IPA 2 SMA Negeri 1 Gondang. Ketuntasan belajar siswa pada aspek kognitif, siklus I menunjukkan ketuntasan siswa 34,38 %, sedangkan pada siklus II 68,75%.Pada aspek afektif, siklus I menunjukkan persentase siswa berkategori sangat baik sebanyak 18,75% dan siswa yang berkategori baik 81,25%. Sedangkang pada siklus II 53,1% berkategori sangat baik, dan 46,88% berkategori baik. Pada aspek psikomotorik, 75% siswa XI IPA 2 SMA Negeri 1 Gondang termasuk kategori baik.
Kata kunci : Problem Based Learning, modul, prestasi belajar, kemampuan berpikir kritis
ABSTRACT
The purpose of the research were to improved critical thinking skills and students learning achievement through the implementation of Problem Based Learning (PBL) learning models in the subject matter solubility and solubility product in class XI IPA 2 SMA Negeri 1 Gondang in the academic year of 2014/2015.
This study was a classroom action research with a model of Kurt Lewin conducted in two cycles. Each cycle begins with the preparation phase and then continued by implementation phase of the cycle consists of action planning, action, observation and evaluation, and reflection. The subjects were students of class XI IPA 2 SMA Negeri 1 Gondang as many as 32 students with research devoted in the subject matter solubility and solubility product. Data obtained through observation, interviews with teachers, daily tests, questionnaires and document review. Data analysis technique used was qualitative techniques supported by quantitative data.
Based on the research results, it can be concluded that (1) Impelemtation of constructivism learning approach through model of Problem Based Learning (PBL) can improve students' critical thinking skills in the subject matter the solubility and solubility results in class XI IPA 2 SMA Negeri 1 Gondang. In the aspect of critical thinking, the first cycle indicates that students who have critical thinking skills with a high category 31.25%, moderate category 31.25% and lower category 37.5%. Whereas in cycle 2, students who have critical thinking skills with a high category 68.75%, moderate category 25% and  lower category 6.25%. (2) Implementation of constructivism learning approach through Problem Based Learning (PBL) can improve student achievement in the subject matter solubility and solubility results in class XI IPA 2 SMA Negeri 1 Gondang. Mastery learning students on cognitive aspects, cycle 1 students demonstrate mastery of 34.38%, while in the second cycle 68.75%.At the affective aspect, cycle 1 shows the percentage of students categorized as much as 18.75% excellent and good students who are categorized 81.25%.While the second cycle 53.12% very good category, and 46.88% good category. On psychomotor aspects, 75% of students of XI IPA 2 SMA Negeri 1 Gondang including good categories.
Keywords: Problem Based Learning, module, learning achievement, critical thinking skills