WordMelodies: Supporting the Acquisition of Literacy Skills by Children with Visual Impairment through a Mobile App
Dragan Ahmetovic, Cristian Bernareggi, Barbara Leporini, Sergio Mascetti · 2023 · ACM Transactions on Accessible Computing · doi:10.1145/3565029
Summary
WordMelodies is a freely available mobile application designed to teach literacy skills to primary school children, with particular attention to accessibility for children with visual impairments or blindness (VIB). The app was developed through an iterative design process involving educators, accessibility specialists, and a congenitally blind expert. It features over 80 exercise types across five interaction families—drag, keyboard, baskets, selection, and table—available in both English and Italian. The researchers evaluated the app through two complementary methods: a controlled user study with 11 children with VIB (ages 5-11, including 2 blind and 9 with low vision) and analysis of remote usage logs from 408 users collected over 21 months. The user study assessed autonomy, ease of use, appreciation, and overall usability using the System Usability Scale adapted for children. A key design challenge was making drag-and-drop interactions accessible via screen reader—traditionally problematic for users with VIB. The team developed specific design principles including large interface elements, high-contrast colors, continuous voice feedback during dragging, and step-by-step tutorials. This approach proved successful, with most children completing drag exercises autonomously.
Key findings
The app achieved a System Usability Scale score of 79, considered "excellent" and higher than the average score of 72 for educational mobile apps. Most children completed exercises autonomously across all five exercise families, including the typically challenging drag-and-drop interactions. Nine of 11 participants solved drag exercises without assistance. Table exercises proved most difficult, with only four participants completing them autonomously. The researchers attribute this to the high number of interactive elements (up to 16 table cells) that must be navigated and tracked, creating cognitive load for both low vision users (small elements) and screen reader users (complex navigation). Remote usage data revealed 408 users performed 29,489 logged interactions over 21 months. iOS devices dominated (68%), with tablets—particularly iPads—preferred over smartphones for this use case. Notably, 81% of users never activated the screen reader, while only 8% always used it, suggesting the app's visual accessibility features (large text, high contrast) served many users with low vision without requiring assistive technology. Italian users frequently attempted English exercises (71% of Italian users), indicating potential for foreign language learning—an identified challenge for children with VIB who lack access to visual teaching materials.
Relevance
This research demonstrates that complex touchscreen interactions like drag-and-drop can be made accessible to screen reader users through careful design—contradicting assumptions that such interactions should be avoided. The specific design principles documented (continuous voice feedback, large targets, color coding, tutorials) are transferable to other educational and mobile applications. For developers of accessible educational apps, the finding that table-based exercises create significant barriers points to the need for careful consideration when presenting multiple interactive elements. The researchers suggest improvements including highlighting current position during navigation and providing selection status feedback. The usage data showing that most users did not activate the screen reader highlights the importance of building visual accessibility features (large text, high contrast, zoom support) directly into apps rather than relying solely on assistive technology compatibility. The app's success with users who have low vision but not complete blindness demonstrates the value of universal design principles that serve a spectrum of visual abilities.
Tags: visual impairment · literacy education · mobile apps · children · screen reader · touchscreen accessibility · inclusive education · edutainment