Table 4.

Results of hierarchical regression analyses predicting math problem solving in kindergarten, Grade 2, and Grade 4.

		Kindergarten		Grade 2		Grade 4
Step		β	ΔR2	β	ΔR2	β	ΔR2
1.	Age	0.200∗	0.05	0.154	0.03	0.060	0.07∗
	Gender	-0.088		-0.030		-0.248∗
2.	Nonverbal intelligence	0.592∗∗∗	0.49∗∗∗	0.187	0.17∗∗∗	0.340∗∗∗	0.16∗∗
	Inhibition	0.116		0.269∗∗		0.154
	Working memory	0.205∗∗		0.235∗		0.099
3.	Number line estimation	-0.121	0.05∗∗	-0.444∗∗∗	0.14∗∗∗	-0.184∗	0.05∗
	Dot estimation	0.190∗∗		-0.052		-0.131
Total R2			0.59∗∗∗		0.34∗∗∗		0.28∗∗∗

^∗p < 0.05, ^∗∗p < 0.001, ^∗∗∗p < 0.001.