Developing interactive e-book of relativity theory to optimize self-directed learning and critical thinking skills

Physics learning in school's aims to foster the ability to think, work and be scientific and communicate as one important aspect of life skills. To achieve that goal, it needs to be supported by the appropriate books. The aim of this research was to develop an interactive e-book of relativity theory to build critical thinking skills and can be used to learn independently for 12th-grade students of Senior High School in even semester. The research method used was research and development. The research stages included literature study, planning, initial product development, expert validation, initial product revision, readability test, and test the ease of operation, revision, and small group test on the actual class using pre-test post-test control group design. Data were collected by using questionnaires and written tests. Data analysis included qualitative and quantitative analysis. Qualitative analysis was used to reference product revision, the practicality of e-book, and to know student response to e-book development result. Quantitative analysis was used to test the effectiveness of e-book. The effectiveness was measured by comparing the N-gain of control class with the experimental class and pre-test and post-test of the experimental class. The results of research showed the e-book of relativity theory that can build the critical thinking skills was prepared according to the stage of scientific approach that is observing, asking, investigating, making conclusions and equipped with adequate experiment simulations. In order for e-books to be used independently, it is necessary to be equipped with a learning instruction manuals, instructions for using the book, materials were prepared from easy to difficult and equipped with exercise questions accompanied by feedback. The results of field test showed that students' critical thinking skills which were using interactive e-books are better than using static books. There was an increase in N-gain of learning outcomes with the moderate category.