This study investigates the outcome of designed source-text materials in context-based physics learning using validated test questions in mechanics. Two groups of students received context-based instruction (experimental group) and one group received content-based instruction (control group). These three groups of students are only different with the (designed and un-designed) source-text materials. The mean-frequency of scores was compared. Furthermore, students were given achievement test and transfer-test. The scores from these two tests were correlated. In general, the results showed that additive source-text materials in context-based instruction significantly improve the performance of the student in mechanics.