The purpose of this study was to design and assess the use of Improvised Instructional Materials (IIM) in teaching physics lessons in Tanga region whereby two Community Secondary Schools (CSS) from Korogwe district and the city of Tanga were selected for implementation of IIM. A total of eight teachers were selected from the sampled schools where by each school provided two physics teachers. The researchers planned and prepared the materials in advance before coaching the teachers on how to implement them. Teachers' ability to execute student centered teaching approaches was assessed before and after coaching. It was found out that the use of improvised instructional materials to run practical lessons has refined and broadens teachers' knowledge on designing and the use of such local materials to carry out physics experiments in CSS.