RESUMEN
Students in Nigerian English language classrooms encounter difficulty in writing. However, the utilisation of metacognitive strategies has the potential to aid students in organising their thoughts during writing for better achievement. Therefore, this study aims to examine the effect of digital graphic organisers on secondary school students' achievement in expository essay writing and the students' perceptions of writing challenges and the impact of the strategy. The study adopted a mixed-methods research design consisting of a within-group experimental design and focus group interview. Five research questions and one hypothesis are formulated to guide the study. An intact class size of 38 students is the subject of the study, while an expository essay writing achievement test and a focus group interview were used for data collection. Percentage, mean and standard deviation, and thematic analysis were used in answering the research questions, while a paired sample t-test was used to test the null hypothesis at 0.05 significance. The study found a statistically significant difference between students' mean achievement scores before and after exposure to digital graphic organiser charts when writing expository essays.