Table 2. Study participant subgroups.

Kindergarten	Montessori (n = 30)	Traditional (n = 28)
Age (SD) Min, max	5.93 (0.89) 4.37–7.83	5.87 (0.75) 4.62–7.83
# of girls	16	16
Fluid intelligence	22.8 (8.79)	21.7 (7.26)
Socio-economic status (SD)	0.64 (0.12)	0.70 (0.13)
Elementary	Montessori (n = 69)	Traditional (n = 74)
Age (SD) Min, max	10.22 (1.53) 7.69–13.4	10.30 (1.21) 7.58–13.3
# of girls	26	38
Fluid intelligence	33.8 (1.98)	32.4 (3.09)
Socio-economic status (SD)	0.73 (0.09)	0.70 (0.11)