. 2011 Jul 25;1(1):76–85. doi: 10.5681/hpp.2011.008

Table 2. The weight of school bags and school bag weight expressed as percentage of body weight (% BW).

Grade level	N	School bag weight (kg) Mean (SD)		School bag weight as % BW Mean (SD)
Grade one	Boys	31	2.3 (0.50)		9.6 (2.09)
	Girls	29	2.7 (0.76)		12.0 (3.47)

Grade two	Boys	29	2.5 (0.54)		9.7 (2.45)
	Girls	30	2.8 (0.67)		10.7 (3.18)

Grade three	Boys	33	3.2 (0.95)		11.5 (4.5)
	Girls	29	3.3 (0.92)		12.0 (4.17)

Grade four	Boys	31	2.9 (0.85)		8.8 (3.58)
	Girls	33	3.0 (0.81)		9.6 (3.00)

Grade five	Boys	29	3.0 (0.87)		7.8 (2.82)
	Girls	33	3.3 (1.22)^a		8.5 (3.13)^b

All	Boys	153	2.8 (0.83)		9.5 (3.42)
	Girls	154	3.1 (0.92) ^c		10.5 (3.62)^d

^aSignificant difference between different grade levels (p < 0.001)

^bSignificant difference between different grade levels (p < 0.001)

^cSignificant difference between boys and girls (p < 0.05)

^dSignificant difference between boys and girls (p < 0.05)