Reading is still difficult for primary school pupils. These pupils are mostly non-native Arabic speakers with poor Arabic command in Jordan. A web-based app can significantly improve pupils' reading skills. This study investigates the effect of a web-based app on pupils' Arabic reading skills and achievement, focusing on information transfer, reading steps, guided reading, and creative reading. The study employs a mixed methods approach, including a quasi-experimental design and interviews, to evaluate the effect of a six-week intervention on Arabic reading skills. The findings showed that a web-based app, LUMIO, significantly improved the reading skills of Grade 4 Jordanian pupils. The experimental group outperformed the control group in post-tests for achievements in information transfer, guided reading, and creative reading compared to the pre-test.