Abstrak Sistem pembelajaran campuran (blended learning) antara pembelajaran daring (online) dan tatap muka (offline) banyak digunakan untuk mendapatkan hasil maksimal. Penelitian ini bertujuan untuk mengembangkan bahan ajar berbasis pembelajaran campuran (blended learning). Metode yang digunakan dalam penelitian ini adalah model pengembangan ADDIE. Model pengembangan ADDIE teridiri dari lima tahapan, yaitu analisis (analyze), perencanaan (design), pengembangan (development), implementasi (implementation), dan evaluasi (evaluation). Bahan ajar ini berisi materi pembelajaran, video pembelajaran, latihan soal, tugas mandiri, dan juga forum diskusi online yang dapat digunakan secara mandiri oleh peserta didik di rumah dan juga dapat digunakan untuk mempersiapkan materi pembelajaran selanjutnya di dalam kelas. Uji kelayakan produk ini dilakukan oleh ahli materi, ahli media, dan ahli pembelajaran. Adapun uji coba produk dilakukan kepada sejumlah guru fisika SMA dan siswa SMA. Kata-kata kunci: bahan ajar, e-learning, blended learning. Abstract This research aims to develop teaching materials based on blended learning of physics atomic core and radioactivity for senior high school. Blended learning based teaching material is to make it easier for teachers and students to learn online and also face to face. The method used in this study is the ADDIE development model. ADDIE development model consists of five stages, namely analysis (analyze), design (design), development (development), implementation (implementation), and evaluation (evaluation). This teaching material contains learning materials, learning videos, exercises, independent assignments, and also online discussion forums that can be used independently by students at home and can also be used to prepare further learning materials in class. The product feasibility test is carried out by material experts, media experts, learning experts and the product trials by physics teachers and students. Keywords: teaching materials, e-learning, blended learning