Evaluating the Effect of Font Size and Line Spacing in Chinese Online Education User Interfaces on Children’s Learning Experience

This study investigates how font size (FS) and line spacing (LS) in online educational apps affect children’s readability, reading speed, learning efficacy, and visual fatigue. A total of 161 children participated in eye-tracking and subjective evaluations. Using ANOVA and correlation analysis, the results show that FS 14px and LS 1.5 are optimal for learning. The study highlights key interface design principles for enhancing human-computer interaction in children’s online education.