<![CDATA[This research which use quasi-experimental with non equivalent control group design was aimed to describe the discovery learning model in increasing students flexibility thinking skills on reaction rates topic. From all of students in the MIA of the 11th grade at SMA Negeri 5 Metro on the even semester 2014-2015 academic year was obtained the MIA1 and MIA3 of the 11th grade as sample by using purposive sampling. The effectiveness of discovery learning model was showed by the significant difference of n-Gain in the control and experiment a classes statistically. The results showed that the average n-Gain in the control and experiment classes 0.35 and 0.47 respecttively. Based on statistical analysis using t-test, the discovery learning model was said effective in increasing students flexibility thinking skills on reaction rates topic.Penelitian yang menggunakan kuasi eksperimen dengan desain Non equivalent Control Group Design ini bertujuan untuk mendeskripsikan pembelajaran model discovery learning dalam meningkatkan keterampilan berpikir luwes siswa pada materi laju reaksi. Dari seluruh siswa kelas XI MIA SMA Negeri 5 Metro semester ganjil tahun ajaran 2014-2015 diperoleh kelas XI MIA1 dan kelas XI MIA3 sebagai sampel menggunakan purposive sampling. Keefektifan model discovery learning ditunjukkan oleh perbedaan n-Gain keterampilan berpikir luwes yang signifikan antara kelas kontrol dan kelas eksperimen secara statistik. Hasil penelitian menunjukkan rata-rata n-Gain keterampilan berpikir luwes pada kelas kontrol dan kelas eksperimen yaitu 0,35 dan 0,47. Berdasarkan pengujian hipotesis menggunakan uji-t, didapat kesimpulan bahwa model pembelajaran discovery learning efektif dalam meningkatkan keterampilan berpikir luwes siswa pada materi laju reaksi.Kata kunci: discovery learning, keterampilan berpikir luwes, materi laju reaksi.]]>
