This study aims: (1) evaluating the validity of the learning tools developed seen from the validation test, (2) evaluating the practicality of the learning tools developed seen from the implementation of the Learning Implementation Plan (RPP) during the learning process, (3) evaluating the effectiveness of the learning tools developed seen from tests of learning outcomes, critical thinking skills, science process skills, attitudes and skills of students. This study uses a Tessmer development research model consisting of 5 steps, namely: (1) self-evaluation; (2) expert opinions (expert review); (3) individual trials (one to one); (4) small group trials; and (5) field test. The trial design is guided by the formative evaluation flow design, which is to find out the validity, practicality, and effectiveness of the developed device. Trial subjects at the individual trial stage consisted of 3 people, at the small group trial stage consisted of 5 people, a field test with 30 students with different levels of knowledge and all subjects were 7th Grade students. The results of the study concluded that: (1) Valid learning tools based on expert opinion include, syllabus, material analysis, teaching material, worksheets, student critical thinking skills assessment sheets, students' science process skills assessment sheets, teacher activity assessment sheets, and activity assessment sheets learners; (2) Learning tools are considered practical based on the activities of teachers and students who are very good from the implementation of lesson plans, self-assessment and students' responses are categorized as good; (3) Learning tools are considered effective based on learning outcomes that have exceeded the Minimum Mastery Criteria that have been set, the ability to think critically and the science process skills are increasing, and the attitudes and skills of students are categorized well.