When engaging learners in searching and designing, the learning materials are of paramount importance, in order to help the learners in the achievement of academic goals and objectives. However, learners being the primary consumers of chemistry content delivered by the teachers, ought to beware of the learning materials that can facilitate their learning. This can well be done if learners participate fully in searching and designing learning materials that correspond with the lesson content. The purpose of this research was to use a Hands-on Instructional Model (HIM) designed to help secondary school teachers actively to engage learners in searching, designing, and manipulating locally made learning materials, in order to facilitate the face-to-face learning of chemistry concepts. The study employed Design-Based Research (DBR) in designing, refining, and implementing HIM, as well as the learning materials designed by the learners following a pragmatic philosophical world-view. The data were collected and analysed by using qualitative research techniques; and the research instruments included Lesson-Observation Protocol, semi-structured interviews, and Focus-Group Discussions. The study involved three intact senior-science classes deliberately selected from three Dar es Salaam community-secondary schools. The results revealed that learners become actively engaged in the lesson, when the learning materials designed by themselves are used. They used materials, like empty water bottles of different sizes, syringes of different sizes, rubber bands, and pegs to prepare locally made apparatus that served as beakers, burettes, droppers, and funnels in titration hands-on activities. In this regard, we recommend teachers involve learners in searching and designing the learning materials to be used in the teaching and learning process, in order to enhance chemistry content mastery and the acquisition of soft learning skills.