Penelitian ini bertujuan untuk menghasilkan Lembar Kegiatan Peserta Didik berbasis Contextual Teaching and Learning (CTL) pada materi transpor membran yang valid, praktis dan efektif untuk melatihkan kemampuan berpikir kritis. Penelitian ini mengacu pada tahapan model pengembangan 4-D (define, design, develop dan disseminate), tetapi pada penelitian ini tahapan disseminate tidak dilaksanakan. Define adalah tahapan menganalisis kurikulum, peserta didik, tugas serta konsep. Design adalah tahapan perancangan LKPD dan terakhir adalah develop yang merupakan tahap pengembangan LKPD dengan dilakukan telaah, validasi dan ujicoba terbatas LKPD yang dikembangkan.Tahapan perancangan LKPD dilaksanakan di Jurusan Biologi FMIPA Universitas Negeri Surabaya, sementara uji coba LKPD dilakukan pada 20 peserta didik SMAN 2 Kediri pada bulan April 2019. Analisis data secara deskriptif kuantitatif. Hasil validitas yang ditinjau berdasarkan penilaian validator, menunjukkan kategori sangat valid dengan persentase keseluruhan aspek sebesar 95,2%. Kepraktisan LKPD berdasarkan keterlaksanaan aktivitas peserta didik mendapatkan persentase 95,5% dengan kategori sangat praktis. Keefektifan ditinjau berdasarkan peningkatan kemampuan berpikir kritis dengan skor n-gain sebesar 0,53 dengan kategori sedang. Sedangkan berdasarkan persentase post-test indikator berpikir kritis secara berturut adalah interpretasi, inferensi, analisis, penjelasan dan evaluasi persentasenya adalah 78,75%; 82,91%; 86%; 76,25% dan 63,75. Keefektifan LKPD berdasarkan respon peserta didik mendapatkan persentase 91,6% dengan kategori sangat efektif. Berdasarkan hasil tersebut dapat disimpulkan bahwa LKPD berbasis Contextual Teaching and Learning (CTL) pada materi transpor membran valid, praktis dan efektif dalam melatihkan kemampuan berpikir kritis.

Kata Kunci :LKPD, CTL, Kemampuan Berpikir Kritis, Transpor Membran

The purpose of this research is to produce a valid, practical and effective CTL-based worksheet that trace the student’s critical thinking abality in membrane transport matter. This research is a development research that refers to the 4-D model (define, design, develop and disseminate), but this research only reach the develop step. Define is the first step that consist of analysing curriculum, student characteristic, task and concept. Then,design is one step to create worksheet design. The last step is develop, this step is doing study, validation, limited trial implementation of the worksheet that have been designed before. The design step of the worksheet was conducted in Biology department of FMIPA UNESA, then the limited trial implementation involved 20 students of Senior High School 2 Kediri on April 2019. Technique of data analysis in this research is descriptive quantitative. The parameter that used in this research include the validity, practicality and efectiveness of student worksheet.The result showed that the validity of student worksheet percentage score  of all of the aspects is 95,2% with very valid category. Then the practicality based on the observation of student activity got the average percentage of 95,5 with very good category. The efectiveness is depend on the enhancement of student critical thinking ability that was measured by test. The enhancement of student critical thinking ability was shown by gain score, that was about 0,53 with middle category. Besides the gain score, the percentage of every indicators of critical thinking are interpretation, inference, analysis, explanation and evaluation. Every indicator’s score are 78,75%; 82,91%; 86%; 76,25% dan 63,75. Then efectiveness was based on the student’s postitive responses that reach about 91,6 including the very good category.

Keywords : Student Worksheet, CTL, Critical Thinking Ability, Membrane Transport