Tujuan penelitian ini adalah mengetahui keefektifan model problem based learnng terhadap penilaian kognitif pada subtema keseimbangan ekosistem. Jenis penelitian ini merupakan penelitian eksperimen dengan desain penelitian yang digunakan adalah one group pretest-posttest design. Penelitian ini dilaksanakan di SD Negeri Candi 03 Semarang pada kelas V yang berjumlah 30 siswa dengan teknik pengambilan sampel jenuh. Berdasarkan hasil analisis data penelitian setelah mendapatkan perlakuan menunjukan bahwa pada pembelajaran subtema 3 keseimbangan ekosistem menggunakan model Problem Based Learning dapat meningkat. Hasil analisis dengan menggunakan uji t diperoleh nilai thitung = 12,835 dengan taraf signifikan 5% didapat nilai ttabel = 1,671 karena thitung (11,7049) > ttabel (1,671), Jadi terdapat perbedaan nilai posttest Subtema Keseimbangan Ekosistem kelas V SDN Candi 03 Semarang sesudah menggunakan model Problem Based Learning.

Kata Kunci: efektivitas, model problem based learning, penilaian kognitif, keseimbangan ekosistem

The purpose of this research is to know the effectiveness of problem based learning model on cognitive assessment on subtheme of ecosystem balance. This type of research is an experimental research with research design used is one group pretest-posttest design. This research was conducted at SD Negeri Candi 03 Semarang in class V which amounted to 30 students with saturated sampling technique. Based on the results of analysis of research data after getting treatment showed that on learning subtema 3 ecosystem balance using Problem Based Learning model can increase. The result of analysis by using t test obtained t value = 12,835 with significance level 5% got ttable value = 1,671 for tcount (11,7049)> ttabel (1,671), So there is difference of posttest value of Subtheme Balancing Ecosystem class V SDN Temple 03 Semarang after using Problem Based Learning model.

Keyword: effectiveness, problem based learning model, cognitive assessment, ecosystem balance