The development of science and technology is very fast and increasingly sophisticated, so schools as educational institutions are required to train critical thinking skills which are one of the skills demanded in 21st century learning. However, the facts found in schools are that the level of students' critical thinking skills is still relatively low. . One of the media that is effectively used to overcome problems related to low critical thinking skills is the E-module. E-module is a form of presenting self-learning material in electronic format which is arranged systematically into the smallest learning units which include animation, audi o, video and navigation so that users are more interactive in learning. This type of research is Research and Development (R&D) research using the Plomp Model. The object of this research is a biology E-module based on a scientific approach to biodiversity material to improve the critical thinking skills of class X high school students. The subjects of this study were three lecturers from the Department of Biology, FMIPA UNP, and one teacher at SMAN 1 Ranah Pesisir as validators for the use of the biology learning E-module. Based on the validation results, it can be concluded that the overall value of the validity results for the development of a biological E-module based on a scientific approach is in the valid category, meaning that the E-module is feasible to be tested in schools.