Keywords: development of teaching devices, science process skills, self-efficacy, group investigation

Science instructions in Junior high school mostly concentrated on cognitive aspect, but ignore affective and psychomotor aspects and science process skills. Most teachings are dominated by teachers (teacher-centered) which tend to be abstract and meaningless. There are some factors that influence teaching performance and one of them is the instructional devices and the kind of teaching approach applied in teaching process. The purpose of this research is to enhance science process skills and self-efficacy of students. The method undertaken by developing instructional devicesof Natural Science of Junior High Schools on the topic of life organization system using cooperative model of group investigation (GI) model. This development research uses Dick and Carey models. There are 9 steps, namely the identification of the general objectives of instructions, conducting teaching analysis, identifying the characteristics of learners, formulating teaching indicators, developing items, developing teaching strategies, developing and selecting instructional devices, designing and executing formative evaluations, and revising instructional devices. The development result of this research consists of Syllabus, PPP, Teaching Material, LKPD, and Evaluation Tools„ which has fulfilled the validity, validity, and effectiveness criteria. The result of the research shows that with the instructional devices of the development result, the science process skills has improved on all indicators with medium and high category, and the attitude of self-confident character has improved with very good category.