ABSTRAK
Penelitian ini bertujuan untuk meningkatkan kemampuan berpikir kritis siswa kelas X MIPA 2 SMA Negeri 6 Surakarta melalui penerapan model Problem Based Learning (PBL).
Penelitian merupakan Penelitian Tindakan Kelas (PTK)  yang dilaksanakan secara bersiklus. Masing-masing siklus terdiri dari 4 tahapan yaitu: perencanaan, pelaksanaan tindakan, observasi, dan refleksi. Subjek penelitian adalah siswa kelas X MIPA 2 SMA Negeri 6 Surakarta tahun pelajaran 2014/2015. Data diperoleh melalui metode tes, observasi, wawancara, dan dokumentasi. Validasi data menggunakan metode triangulasi. Data hasil tes, observasi, wawancara, dan dokumentasi dianalisis dengan teknik analisis deskriptif kualitatif yang terdiri dari tiga komponen, yaitu: reduksi data, penyajian data, dan penarikan kesimpulan atau verifikasi.  Prosedur penelitian menggunakan metode spiral.
Hasil penelitian menunjukkan bahwa kemampuan berpikir kritis siswa meningkat dari Prasiklus, Siklus I, Siklus II, dan Siklus III. Kemampuan berpikir kritis siswa rata-rata meningkat dari 35,22% menjadi 60,62%. Aspek interpretasi meningkat dari 41,13% menjadi 66,94%. Aspek analisis dari 28,23% menjadi 54,84%. Aspek kesimpulan dari 38,71% menjadi 62,90%. Aspek evaluasi meningkat dari 43,55% menjadi 65,32%. Aspek penjelasan dari 27,42% menjadi 55,65%. Aspek pengaturan diri dari 32,26% menjadi 58,06%.
Berdasarkanhasilpenelitiandisimpulkanbahwapenerapanmodel Problem Based Learningmeningkatkankemampuanberpikirkritissiswakelas X MIPA 2 SMA Negeri 6 Surakarta TahunPelajaran 2014/2015.
Kata Kunci: Kemampuan Berpikir Kritis,ModelProblem Based Learning
ABSTRACT
This study was aimed to improve critical thinking ability of the student in class of X MIPA 2 SMA Negeri 6 Surakarta in learning biology through the implementation of Problem Based Learning model.
This research was a ClassroomAction Research which consists of three cycles. Each cycle consists of four stages: planning, action, observation, and reflection. The subject of this research were the students in class of X MIPA 2 SMA Negeri 6 Surakarta academic year 2014/2015. The data were collected using critical thinking test, observation sheet, interview, and documentation. The data were validated using triangulation method. The data of test, observation, interview, and documentation were analyzed using qualitative analysis which was done in three components, they were: data reduction, data presentation, and drawing the conclusion or verification. The research procedure was using spiral method.
The results show that students critical thinking ability was increased in Pre-cycle, Cycle I, Cycle II and Cycle III. The average of students critical thinking ability increase from 35,22% to 60,62%. Aspect of interpretation rise from 41,13% to 66,94%. Aspect of analysis rise from 28,23% to 54,84%. Aspect of inference increase from 38,71% to 62,90%. Aspect of evaluation increase from 43,55% to 65,32%. Aspect of explanation rise from 27,42% to 55,65%. Aspect of self-regulation rise from 32,26% to 58,06%.
This research’s conclusion was the implementation of Problem Based Learning model can improve critical thinking ability of the student in X MIPA 2 class at SMA Negeri 6 Surakarta academic year 2014/2015.
Keywords: Critical Thinking Skill, Problem Based Learning Model