Optimizing blackboard visibility for enhancing classroom ergonomics

Abstract

Effective teaching and learning are significantly influenced by the classroom ergonomics, particularly the visibility of blackboards, which is affected by factors such as daylight variations, chalk colour, viewing angles and blackboard areas. While previous research has often examined these factors in isolation, this study explored their individual and combined effects to provide a cohesive framework for optimizing visibility. Luminous environment metrics were quantitatively assessed using fixed and handheld measurement devices, while student feedback was collected through surveys. Spearman's Rank Correlation revealed a strong positive relationship between contrast and visibility scores ( $r_s$  = 0.75, p < 0.001), while the Kruskal-Wallis test confirmed significant effects of viewing angle (H = 1145.24, p < 0.001) and chalk colour (H = 798.44, p < 0.001) on visibility. Despite yellow chalk exhibiting the highest contrast ratio (3.005), subjective assessments favoured green chalk, likely due to its reduced visual fatigue and perceptual comfort. Conversely, red chalk provided the least visibility, limiting its practical use. Visibility was highest during morning hours (9 AM–11 AM), particularly in blackboard areas closer to natural light sources. These findings offer insights for designing classrooms that enhance visual comfort, reduce eye strain and support student engagement in energy-efficient learning spaces.