Penelitian ini adalah Penelitian pengembangan dengan menggunakan Penelitian Desain Pendidikan (Educational Design Research) model evaluasi formatif Tessmer. Penelitian ini adalah penelitian pengembangan yang bertujuan untuk mendeskripsikan validitas, kepraktisan dan keefektifan hasil pengembangan Lembar Kegiatan Peserta Didik biologi terhadap keterampilan berpikir kritis peserta didik SMP kelas VIII. LKPD biologi yang dikembangkan berupa konsep sistem dalam tubuh manusia, yaitu 1) sistem gerak, 2) sistem pencernaan dan 3) sistem peredaran darah. Penelitian dilakukan selama 6 bulan (Juli - Desember). Uji validasi pada tiga pakar ahli pendidikan IPA, uji coba kelompok kecil pada empat peserta didik dan  uji coba lapangan pada tiga belas peserta didik kelas VIII SMP Hasbunallah. Data diperoleh dari instrumen penelitian berupa lembar penilaian validitas, angket keterlaksanaan dan efektifitas. Analisis data dilakukan secara deskriptif kuantitatif. Hasil penelitian menunjukkan Lembar Kegiatan Peserta Didik Biologi SMP oleh tiga orang ahli menunjukkan validitas dengan kategori sangat valid. kepraktisan isi, harapan dan aktual Lembar Kegiatan Peserta Didik dinyatakan sangat baik. Nilai rerata keefektifan berpikir kritis dengan kategori tinggi. Jadi, hasil penelitian pengembangan kesimpulannya Lembar Kegiatan Peserta Didik Biologi terhadap Keterampilan Berpikir Kritis Peserta Didik SMP layak digunakan dalam proses pembelajaran.

This research is a development research using the Educational Design Research (Educational Design Researchformative evaluation model Tessmer. This research is a development research that aims to describe the validity, practicality and effectiveness of the results of developing Biology Student Activity Sheets on critical thinking skills of VIII grade junior high school students. LKPD biology developed in the form of the concept of systems in the human body, namely 1) the movement system, 2) the digestive system, and 3) the circulatory system. The study was conducted for 6 months (July - December). Validation test on three science education experts, small group trial on four students and field trial on thirteen class VIII students of SMP Hasbunallah. Data were obtained from research instruments in the form of validity assessment sheets, implementation and effectiveness questionnaires. Data analysis was carried out descriptively quantitatively. The results showed that the Junior Biology Student Activity Sheet by three experts showed validity with a very valid category. the practicality of the contents, expectations and actuality of the Student Activity Sheets is stated to be very good. The average value of the effectiveness of critical thinking in the high category. So, the results of the research development concluded that the Biology Student Activity Sheet on the Critical Thinking Skills of Junior High School Students was appropriate to be used in the learning process.