Continuous Professional Development (CPD) programme include community of practice, action research, training, and award-bearing. CPDs also include deficit, cascade model, standard-based model, and coaching and mentoring. These CPD programme have been used in acquiring and disseminating new ideas and practices. In Rwanda, towards the effectiveness of teaching and learning of mathematics and science subjects, secondary schools' teachers of the aforementioned subjects have been involved in the development of the scripted lessons. This study investigates the skills gained by mathematics and science instructors through the preparation of scripted lessons for continuous professional development. Data were gathered using a qualitative design through rating questionnaire made of Likert-scale and of open-ended questions. Only mathematics and science teachers who developed scripted lessons were targeted for the study. The interpretive technique was employed to analyze findings. Results showed the improved teachers' subject content knowledge, pedagogical understanding, lesson planning, and collaborative skills. These acquired knowledge and skills improved their instructional efficacy as well as students' learning results. The study recommends the involvement of teachers in the development of the CPD programme materials to help them gaining more knowledge and skills. Further, additional research is needed to investigate the long-term impact of involving teachers in CPD programme activities.