Penelitian ini bertujuan untuk mengembangkan sumber belajar siswa berupa Lembar Kegiatan Siswa (LKS) berbasis Inkuiri Terbimbing pada materi fotosintesis di kelas VIII SMP. Kualitas Lembar Kegiatan Siswa Berbasis Inkuiri Terbimbing pada materi fotosintesis berdasarkan aspek kevalidan, kepraktisan, dan respon siswa. penelitian ini merupakan penelitian pengembangan (Research and Development). Penelitian ini menggunakan model pengembangan 4D (define, design, development dan desiminate) yang dilakukan hanya sampai pada tahap ke tiga yaitu development. Hasil penelitian ini berupa Lembar Kegiatan Siswa (LKS) berbasis inkuiri terbimbing pada materi fotosintesis untuk siswa kelas VIII SMP Negeri 6 Tarakan . Hasil penelitian menunjukkan kualitas produk Lembar Kegiatan Siswa(LKS) berbasis Inkuiri Terbimbing yang dihasilkan telah memenuhi aspek kevalidan dan kepraktisan. Kriteria nilai 84%(Sangat valid), diperoleh dari masing-masing dari ahli valiadator yaitu dari ahli media 92% (Sangat valid), ahli materi 83% (Sangat valid), dan ahli kebahasaan 77% (valid). Aspek kepraktisan berdasarkan hasil penilaian respon guru memperoleh nilai 80% (sangat praktis). Hasil angket respon siswa uji coba terbatas memperoleh persentase sebesar 85% (Sangat menarik) dan pada uji coba Luas memperoleh persentase sebesar 86% (Sangat menarik). Berdasarkan hasil penelitian, dapat disimpulkan bahwa Lembar Kegiatan Siswa (LKS) berbasis Inkuiri Terbimbing layak dan praktis untuk digunakan sebagai sumber pembelajaran di sekolah.
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This development research aimed to develop students' learning resources inthe form of Student Worksheet (LKS) based on guided inquiry in photosynthesis material for students of class VIII of Junior High School. The quality of Student Worksheet based on guided inquiry in photosynthesis material based on aspects of validity, practicality, and students’ response. This is a development research which apply Research and Development (R&D). This research used 4D development model (define, design, development and desiminate) conducted only until the third stage which is development. The results of the research was a Students Worksheet (LKS) based on guided inquiry in photosynthesis material for students of class VIII of SMPN 6 Tarakan. The results showed the quality product of Students Worksheet (LKS) based on guided inquiry that produced had been fulfilled the aspect of validity and practicality. The score criteria with a percentage of 84 % (very worthy), products produced is categorized as valid by the validation of media experts with a percentage of 92% (very worthy), subject matter experts with a percentage of 83%, and linguistic experts with a percentage of 77% (worthy). Aspects of practicality based on the assessment of teachers with a percentage of 80% (very worthy). The results of students’ questionnaire responses in limited test obtain a percentage of 85% (very interesting) and on a comprehensive trials obtain a percentage of 86% (very interesting). Based on the results, it can be concluded that the Students’ Worksheet (LKS) based Guided Inquiry feasible and practical to use as a learning resource for the school.