Table 2. Average letter size, viewing distance and visual acuity demand, and comparison between different grades (grade 4 to 8 and grade 9 to 12 group) and schools (n = 8) in 33 classrooms.

Variable	Mean (SD)	Range	Between grade groups (Independent t test statistic, p value)	Between schools (One way ANOVA, F (7,25) statistic, p value)
Smallest letter height (cms)	2.0 ±0.56	1–3.10	0.136	0.392
Distance from centre of board to front row (m)	2.76±0.66	1.8–4.14	0.244	0.139
Longest distance student seated (m)	6.56±1.16	4.1–8.7	0.128	0.076
Maximum distance VA threshold demand (logMAR)	0.31±0.17	-0.06, 0.62	0.055	0.113
Minimum Visual demand at front row (desk position 2) in logMAR	0.56±0.18	0.14–1.04	0.132	0.132