AbstrakPenelitian ini bertujuan untuk mendeskripsikan aktivitas guru serta meningkatkan sikap ilmiah dan hasil belajar dengan menerapkan model problem based learning pada materi sistem pencemaran lingkungan di kelas VIIB SMPN 11 Kota Bengkulu. Jenis penelitian adalah penelitian tindakan kelas yang dilakukan dalam dua siklus. Setiap siklus terdiri atas empat tahap yaitu perencanaan, pelaksanaan, observasi dan refleksi. Subjek penelitian ini adalah guru dan siswa kelas VIIB SMPN 11 Kota Bengkulu tahun ajaran 2016/2017. Variabel penelitian ini adalah model problem based learning, sikap ilmiah, dan hasil belajar. Instrumen penelitian berupa lembar observasi untuk mengetahui aktivitas guru dan sikap ilmiah, sedangkan lembar tes digunakan untuk mengetahui hasil belajar. Hasil analisis data observasi aktivitas guru siklus I diperoleh skor rata-rata 24 (baik), dan di siklus II 28 (baik). Hasil analisis data observasi sikap ilmiah siswa siklus I diperoleh skor rata-rata 17,71 (cukup), siklus II menjadi 20,74 (baik). Pada hasil belajar kompetensi pengetahuan siklus I mendapatkan persentase 66,66%, siklus II menjadi 84,85%, pada hasil belajar kompetensi sikap siklus I mendapatkan persentase 69,69%, siklus II menjadi 100%, pada hasil belajar kompetensi keterampilan siklus I mendapatkan persentase 81,81%, siklus II menjadi 100%. Disimpulkan bahwa model problem based learning dapat meningkatkan sikap ilmiah dan hasil belajar siswa kelas VIIB SMPN 11Kota Bengkulu. AbstractThis study aimed to describe the teacher activity and improve scientific attitude and learning outcomes by applying Problem Based Learning model on environmental pollution topic in class VIIB SMPN 11 Kota Bengkulu. This type of research was Classroom Action Research with descriptive method. This study consists of 2 cycles, each cycle consists of four phases: planning, action, observation and reflection. The subjects were biology teacher and students of class VIIB SMPN 11 Kota Bengkulu school year 2016/2017. The variables of this research were Problem Based Learning model, scientific attitude, and learning outcomes. The research instrument was an observation sheet to determined teacher activity and scientific attitude, while the test sheet was used to determined the learning outcomes. The average score result for data analysis of teacher activity observation in first cycle was 24 (good), while in second cycle was 28 (good). The average score result for data analysis of scientific attitude observation in first cycle was 17,71 (enough), while in second cycle was 20,74 (good). The result of cognitive learning outcomes in first cycle was 66,66%, while in second cycle was 84,85%. The result of affective learning outcomes in first cycle was 69,69%, while in second cycle was 100%. The result of psychomotor learning outcomes in first cycle was 81, 81%, while in second cycle was 100%. It was concluded that the problem based learning model can improve the scientific attitude and learning outcomes of the students of in class VIIB SMPN 11 Kota Bengkulu.