In Nairobi’s informal settlements, many students struggle with mathematics due to inadequate teacher training and resources. Aimed at improving student achievement in Kenya's business education sector through targeted teacher training sessions. Encouragingly, students showed a statistically significant improvement of 15% in mathematics scores after participating in the workshops. Professional development workshops significantly boosted teachers’ pedagogical skills and resource availability, translating to better student performance in math. Expand professional development programmes for all Nairobi’s informal settlement schools to further improve educational outcomes.