. Author manuscript; available in PMC: 2024 Jan 26.

Published in final edited form as: Dev Psychol. 2012 Mar 5;48(5):1229–1241. doi: 10.1037/a0027433

Table 4.

Means (Standard Deviations) and Ranges of Assessments Used in Study 2 (N = 42)

Task	M (SD)	Range
Spatial skill (CMTT, items correct of 22; chance = 25%)	12.8 (4.26)	4–21
Vocabulary (PPVT-III standardized score)	108.4 (15.9)	56–44
Number line knowledge (0–100 number line linear R²)	0.57 (0.30)	0.00–0.96
Approximate symbolic calculation (items correct of 16; chance = 50%)	13.4 (2.15)	8–16
Approximate nonsymbolic calculation (items correct of 16; chance = 50%)	12.5 (1.37)	9–15

Note. CMTT = children’s mental transformation task; PPVT-III = Peabody Picture Vocabulary Test–Third Edition.