<![CDATA[The aim of this research was to describe the effectivity of problem solving learning to increase students originality thinking ability on the reactions rate of chemistry subject. This research used Non Equivalent Control Group Design and the sample was choosen using purposive sampling. Population of the research, was tenth grade students of SMA Negeri 1 Gedong Tataan at first semester in the 2013/2014 year and the sample were, XI science 1 and XI science 3. The effectivity of problem solving learning was analyzed based on the differences of significant n-Gain between experiment and control classes. The results showed that the average n-Gain score in experimental and control were 0,67 and 0,38. Based on hyphothesis testing (t-test), it can be concluded that problem solving learning is effective to increase students originality thinking ability on the reactions rate of chemistry subject.Tujuan penelitian ini adalah untuk mendeskripsikan efektivitas model pembelajaran problem solving dalam meningkatkan kemampuan berpikir orisinil siswa pada materi laju reaksi. Metode penelitian ini adalah kuasi eksperimen dengan Non Equivalent Control Group Design. Sampel penelitian dipilih menggunakan teknik purposive sampling. Populasi dalam penelitian ini adalah semua siswa kelas XI IPA SMA Negeri 1 Gedong Tataan semester ganjil Tahun Pelajaran 2013/2014 dan sampel penelitian adalah kelas XI IPA1 dan XI IPA3. Efektivitas pembelajaran problem solving diukur berdasarkan perbedaan n-Gain yang signifikan antara kelas eksperimen dan kelas kontrol. Hasil penelitian menunjukkan bahwa rata-rata n-Gain kemampuan siswa dalam berpikir orisinil pada kelas eksperimen dan kelas kontrol sebesar 0,67 dan 0,38. Berdasarkan pengujian hipotesis (uji-t), diketahui bahwa model pembelajaran problem solving efektif dalam meningkatkan kemampuan berpikir orisinil siswa pada materi laju reaksi.Kata kunci: kemampuan berpikir orisinil, laju reaksi, model problem solving]]>
