This dataset was collected for the fulfillment of the first author's PhD studies. It was collected in two phases. Preliminary data investigated the status of tutors' mathematical knowledge for teaching. A lesson planning intervention framed within the technological and pedagogical content knowledge framework was provided to an experimental group of tutors. Then, after-intervention data were collected in the form of improved lesson plans, classroom observation, and student performance. This dataset is important for tutors, researchers, and policymakers to gain insights into the effectiveness of the implemented intervention, inform future educational strategies, and enhance the overall quality of mathematical teaching.