The use of low-tech SMS messaging for education has grown in recent years, particularly recently as a result of the Covid-19 pandemic. SMS can be cost-effective, while personalised learning can be beneficial for girls. However, the empirical evidence base for such interventions is currently extremely limited, and further research is needed to understand observations in practice and how they can be enhanced to further improve learning outcomes and the design of programmes. This study will use a rigorous, sequential mixed-methods research design undertaken in partnership with M-Shule, a Kenya-based SMS-based personalised learning platform.