Penelitian ini bertujuan untuk menghasilkan LKS berbasis problem solving pada materi perubahan lingkungan untuk melatihkan keterampilan berpikir kritis dan kemampuan argumentasi tertulis siswa kelas X SMA yang valid, praktis dan efektif. Dalam penelitian ini menggunakan model pengembangan model 4-D namun tahap disseminate tidak dilakukan. LKS yang dikembangkan diujicobakan terbatas kepada 20 siswa kelas X SMAN 1 Gedeg. Validitas LKS ditentukan berdasarkan perolehan skor hasil validasi, kepraktisan LKS ditentukan berdasarkan aktivitas siswa, serta keefektifan ditentukan berdasarkan ketuntasan hasil belajar dan respon siswa. Hasil analisis validitas menunjukkan skor validasi sebesar 3,45 dengan kategori valid. Kepraktisan LKS memperoleh skor keterlaksanaan sebesar 92,5% dengan kategori sangat praktis. Keefektifan berdasarkan kenaikan aspek berpikir kritis dan kemampuan berargumentasi siswa, seluruh siswa mengalami kenaikan keterampilan berpikir kritis dan kemampuan argumentasi tertulis, berdasarkan hasil analisis respon memperoleh skor sebesar 91,31% dengan kategori sangat efektif. Hasil penelitian menunjukkan bahwa LKS yang dikembangkan dinyatakan layak berdasarkan validitas, kepraktisan dan keefektifan.

Kata kunci : Lembar Kegiatan siswa, keterampilan berpikir kritis, kemampuan argumentasi tertulis, Perubahan Lingkungan, Problem solving.

This study aimed to produce student worksheet based on problem solving on environmental change to train critical thinking skills and written argumentation skills of high school class X students which valid, practical, and effective. In this study the development model refers to the 4-D model but the disseminate stage is not implemented. The student worksheet was tested to 20 students class X of SMAN 1 Gedeg. The validity of student worksheet is determined based on the acquisition of the results of the validation score, the practicality of the worksheet is determined based on the activities of the students, and the effectiveness is determined based on the completeness the results of learning and student responses to the worksheet. The results of the analysis show that the student worksheet obtained a validation score of 3.45 with a valid category. The practicality of student worksheet obtained an implementation score of 92.5% with a very practical category. Effectiveness based on the increase in aspects of critical thinking and the students ability to argue, as many as 100% of students experience an increase. Then the effectiveness reviewed based on the results of the response analysis scores 91.31% with a very effective category. The results of the study showed that the worksheet was suitable based on validity, practicality, and effectiveness.

Keywords: Student worksheet, critical thinking skills, written argumentation skills, Environmental Change, Problem solving