Biotechnology is important to learn to prepare students to be able to innovate in the future, but students still have difficulty learning biotechnology materials due to low understanding of learning materials, and students are not directly involved in learning so that it hampers students' ability to think critically. However, the development of SETS-based teaching materials with formative assessments in junior high school biotechnology learning as an effort to improve critical thinking skills is still rarely done. The purpose of this study was to develop and test the feasibility of a SETS-based biotechnology e-module with formative assessment in improving the critical thinking skills of grade IX junior high school students. The research procedure used is a 3-D model which is a modification of the 4-D model, namely Define, Design, and Develop. The research instruments used were material validation questionnaires, media validation questionnaires, and readability test questionnaires. The results of validation by a lecturer and a teacher who are both material experts and media experts show that the SETS-based e-module with formative assessment has a feasibility percentage of 88.93% with a very feasible category. The results of the readability test by 33 students showed the percentage of e-module readability was 92.01% with a very good category. Thus, an e-module based on SETS with formative assessment is included in the very feasible category so that it can be applied to improve students' critical thinking skills in biotechnology materials. For further research, this product development is recommended so that it can be tested for effectiveness and implemented in classroom learning.