The flipped classroom model is an innovative and increasingly popular pedagogical approach in higher education. However, despite its increasing popularity, few studies have elaborated on specific strategies to implement a flipped classroom model. This study has as its purpose to investigate the effect of an extended flipped classroom model for fully online learning and its interaction with working memory capacity on students' reading comprehension by means of a quasi-experimental study with a 2 x 2 factorial design in which a total of one hundred and twelve students participated for nine weeks. The two-way analysis of variance revealed that students' reading comprehension ability increased significantly in the extended flipped classroom model compared to that of students in the original flipped classroom. Students with a high WMC also largely outperformed their counterparts with a low WMC in reading comprehension, an interaction effect being thus identified between the instructional model and WMC as well. This paper concluded with a call to implement an extended flipped classroom model in reading courses and to undertake more specific types of research into the effectiveness of this model across different settings and language skills.