THE EFFECT OF ARTICULATE STORYLINE ASSISTED GUIDED DISCOVERY LEARNING ON STUDENTS' CRITICAL THINKING ABILITY IN LEARNING GEOGRAPHYCritical thinking is a skill that must be honed and developed in 21st-century learning because it is useful in studying and solving problems that arise. Based on its advantages, the Guided Discovery Learning model is able to improve the ability to think critically. On the other hand, the use of articulate storyline media is able to clarify the information or message conveyed so that it can facilitate the learning process. The purpose of this study was to determine the effect of Guided Discovery Learning assisted by articulate storyline media on students' critical thinking skills in geography learning. The research design used a Quasi-Experimental design with a post-test-only group design. The research subjects included students of grade X5 and grade X6, with experimental class (class X5) and control class (class X6). The determination of the class is done by means of Random Sampling through a lottery. The results showed that the mean value of the post-test of critical thinking skills of experimental class students with Guided Discovery Learning model treatment assisted by articulate story media was higher (86.09) than the control class (79.87). The results of hypothesis testing with an independent sample test showed a significance value of 0.000 less than 0.05. These results prove that the Guided Discovery Learning model, assisted by articulate storyline media, has a positive impact on students' critical thinking skills. There are other findings in this study, namely the stimulus and proof stages as the most dominant stages affecting critical thinking skills.Pemikiran yang kritis menjadi suatu keterampilan yang harus diasah dan dikembangkan dalam pembelajaran abad 21, karena berguna dalam mengkaji dan menyelesaikan permasalahan yang muncul. Berdasarkan keunggulan yang dimilikinya, model Guided Discovery Learning mampu meningkatkan kemampuan untuk berpikir kritis. Disisi lain, penggunaan media articulate storyline mampu memperjelas informasi atau pesan yang disampaikan, sehingga dapat memperlancar proses pembelajaran. Tujuan penelitian ini yaitu untuk mengetahui pengaruh Guided Discovery Learning berbantuan media articulate storyline terhadap kemampuan berpikir kritis bagi siswa pada pembelajaran geografi. Desain penelitian menggunakan rancangan Quasi Experimental with post-test only group design. Adapun subjek penelitian meliputi siswa kelas X5 dan kelas X6, dengan kelas eksperimen (kelas X5) dan kelas kontrol (kelas X6). Penentuan kelas tersebut dilakukan dengan cara random sampling melalui undian. Hasil penelitian menunjukkan bahwa nilai rerata post-test kemampuan berpikir kritis siswa kelas eksperimen dengan perlakuan model Guided Discovery Learning berbantuan media articulate storyline lebih tinggi (86.09) dibandingkan kelas kontrol (79.87). Hasil uji hipotesis dengan independent sample test memperlihatkan nilai signifikansi sebesar 0.000 kurang dari 0.05. Hasil tersebut membuktikan bahwa model Guided Discovery Learning berbantuan media articulate storyline berpengaruh terhadap kemampuan berpikir kritis siswa. Terdapat temuan lain pada penelitian ini, yaitu tahapan stimulus dan pembuktian sebagai tahapan yang paling dominan mempengaruhi kemampuan berpikir secara kritis.