This paper reports on a study that explored five student-teachers' beliefs regarding the usability of three digital flashcard websites that can be used in a blended learning approach in English Language Teaching (ELT) classrooms. These student-teachers, who had previous teaching experience, were students on a year-long Master of Arts (MA) programme at Coventry University. Adopting a mixed-method research design, this study incorporated aspects of both surveys and case studies to explore different variables that could have an effect on the use of digital flashcards in blended learning classrooms. The websites' design features appeared to create two extreme reactions in student-teachers, suggesting it might be a significant factor in shaping their beliefs. [For the complete volume, "Flipping the Blend through MOOCs, MALL and OIL--New Directions in CALL," see ED585277.]