ABSTRAKTujuan penelitian ini adalah untuk meningkatkan: (1) kemampuanberpikir kritis siswa pada materi pokok Termokimia melalui penerapan modelpembelajaran Problem Based Learning (PBL) dilengkapi Macromedia Flash,(2) prestasi belajar siswa pada materi pokok Termokimia melalui penerapanmodel pembelajaran Problem Based Learning (PBL) dilengkapi MacromediaFlash.Penelitian ini merupakan Penelitian Tindakan Kelas yang dilaksanakandalam dua siklus, dengan tiap siklus terdiri atas perencanaan tindakan,pelaksanaan tindakan, observasi dan refleksi. Subjek penelitian adalah siswakelas XI MIA 1 SMA Negeri 2 Karanganyar yang berjumlah 37 siswa. Sumberdata berasal dari guru dan siswa. Teknik pengumpulan data adalah dengan tesdan non tes (observasi, wawancara, kajian dokumen dan angket). Analisis datamenggunakan teknik analisis deskriptif kualitatif.Hasil penelitian menunjukkan bahwa: (1) penerapan modelpembelajaran Problem Based Learning (PBL) dilengkapi Macromedia Flashdapat meningkatkan kemampuan berpikir kritis siswa pada materi pokokTermokimia. Hal ini dapat dilihat dari persentase kemampuan berpikir kritissiswa adalah 72,97% pada siklus I dan meningkat menjadi 89,19% pada siklus II,(2) penerapan model pembelajaran Problem Based Learning (PBL) dilengkapiMacromedia Flash dapat meningkatkan prestasi belajar siswa pada materi pokokTermokimia. Peningkatan prestasi belajar siswa dapat dilihat dari aspek kognitifdan aspek afektif. Pada aspek kognitif persentase ketuntasan siswa pada siklus Iadalah 54,05% dan meningkat menjadi 78,38% pada siklus II. Sedangkan padaaspek afektif menunjukkan bahwa terdapat peningkatan persentase dari 83,78%pada siklus I menjadi 91,89% pada siklus II. Sedangkan aspek psikomotor yanghanya dilakukan pada siklus I sebesar 100%.Kata Kunci: Problem Based Learning, Macromedia Flash, Kemampuan BerpikirKritis, Prestasi Belajar, TermokimiaABSTRACTThe purposes of the study were to improve: (1) the student’s criticalthinking ability in the subject matter of thermochemistry by Problem BasedLearning (PBL) learning model with macromedia flash, (2) the student’sachievement in the subject matter of thermochemistry by Problem BasedLearning (PBL) learning model with macromedia flash.This research was a classroom action research which was held in twocycle, each cycle consist of planning, acting, observing and reflecting. Theresearch subject was the student of class XI science 1 in SMA Negeri 2Karanganyar that contains of 37 student. The data was taken from teachers andstudents. Data were obtained by test and non test (observations, interviews,document reviews and questionnaires). The data were analyzed using techniqueof qualitative descriptive analysis.The research’s result showed that: (1) the implementation of ProblemBased Learning (PBL) learning model with macromedia flash could improve thestudent’s critical thinking ability in the subject matter of thermochemistry. Itcould be seen from the percentase of student’s critical thinking ability was72,97% in cycle I and incerased to 89,19% in cycle II, (2) the implementation ofProblem Based Learning (PBL) learning model with macromedia flash couldimprove the student’s learning achievement in the subject matter ofthermochemistry. While the incerased of student’s achievement could be seenfrom cognitive and affective aspect. In cognitve aspect, the students learningcompletion was 54,05% in cycle I and incerased to 78,38% in cycle II. While inaffective aspect, the percentase incerased from 83,78 % in cycle I to 91,89% incycle II. Meanwhile, psychomotoric aspect which was done in cycle one was100%.Key Words: Problem Based Learning, Macromedia Flash, Critical ThinkingAbility, Student’s Achievement, Thermochemistry