Dissertation (MA Education)This study designed and developed competence based instructional materials to support geography teachers adapt and teach the competence based geography curriculum in O-level secondary schools. The objectives of this study were to: design an exemplary competence based instructional lesson materials for teaching soil in O - level secondary schools; assess the practicality of the designed materials through classroom try-out in selected schools; evaluate the effectiveness of the materials in the implementation of the competency based geography curriculum in O – level secondary schools. The study was conducted in Dodoma area. The study focused on promoting competence based geography curriculum in O-level secondary schools where traditional teaching approach dominated classroom practices. The study adopted developmental approach using Quasi-Experimental design. Experts in curriculum design and geography teachers appraised the designed exemplary lessons materials. Two schools were used in formative and summative evaluation, involving experimental and control school. The study collected qualitative and quantitative data through questionnaire, interview, observation, documentary review and pre-post test. Purposive sampling was used in selecting the participants. Data were analyzed through descriptive statistical, content analysis and paired t test The findings indicated that teachers and students were interested with the materials. Paired t test indicated a significant improvement and Average Normalized gain (g) showed that experimental school performed higher than control school. The study recommends teachers to find and use designed and competences based materials and adopt student centered approach.The study suggests researchers to conduct other similar studies involving more than one experimental school.