Table 1 Variables distribution

Hour

10855

10.81 (1.493)

(10.7910.84)

11 (1012)

− 0.085

Age group

10363

8.92 (1.667)

(8.898.96)

9 (810)

− 0.226

N. of regular educ. classes

10853

15.077 (4.667)

(14.9915.16)

15 (1218)

0.15

N. of special educ. classes

10853

1.44 (1.437)

(1.421.47)

1 (02)

1.168

Average N. of students in regular educ. classes

10853

27.138 (3.694)

(27.0727.21)

27.17 (24.4429.6)

− 0.06

Average N. of students in special educ. classes

10853

28.695 (3.433)

(28.6328.76)

29.06 (26.3831.15)

− 0.308

Gender N (%)

N = 10585

boy

7251 (69.3%)

girl

3334 (30.7%)

Event place N (%)

N = 10855

Classroom

1662 (15.3%)

Corridor

851 (7.8%)

Sportsground

1341 (12.4%)

Sports hall

390 (3.6%)

Stairs

292 (2.7%)

Yard

4216 (38.8%)

Otherwise

2103 (19.3%)

Event term N (%)

N = 10855

Before-after school

284 (2.6%)

Break

5146 (47.4%)

Lesson

1479 (13.6%)

Sports class

330 (3%)

Otherwise

3616 (33.3%)

Anatomic place main N (%)

N = 10855

Foot

1810 (16.7%)

Hand

2410 (22.2%)

Head

5853 (53.9%)

Other

782 (7.2%)

Injury cause N (%)

N = 10855

Game

4819 (44.4%)

Height

354 (3.3%)

Slipping

2534 (23.3%)

Violence

579 (5.3%)

Otherwise

2569 (23.7%)

Injury type N (%)

N = 10852

Medium/deep incision

52 (0.4%)

Superficial incision

1433 (13.2%)

Light local burn

12 (0.1%)

Rubbing tear

707 (6.5%)

Trauma

7608 (70.1%)

otherwise

1040 (9.6%)

Teachers and students' closeness

10766

67.07 (12.723)

(66.8367.31)

66.78 (58.6575.51)

0.208

Efforts involved

9648

62.533 (13.069)

(62.2762.79)

61.91 (54.1569.29)

0.299

Violence cases

10766

10.337 (3.975)

(10.2610.41)

10.42 (8.0612.63)

0.149

Teachers' satisfaction

10517

73.849 (9.238)

(73.6774.02)

75.4 (69.0580.12)

− 0.83

Parents involvement

9815

86.528 (7.29)

(86.3886.67)

87.5 (83.8291.67)

− 1.311

General positive feeling

10766

77.947 (10.352)

(77.7578.14)

77.56 (71.7584.41)

− 0.313