| Abstract: | This study investigated the effectiveness of instruction on spatial skills. It examined the effect of instruction of liquid horizontality on the performance on Piagetian Water Level Task (WLT) from a developmental perspective through two substudies. In Study 1, the WLT was administered to 256 boys and 230 girls of ages 9, 10, 12, 14, and 17 from Beijing, China, before and after instruction. The results indicate that the instruction effect was significant for the 6th (p < .05) and 8th graders (p < .001) but not for the 4th, 5th, and 11th graders. Study 2 examined instruction effect in contrast with practice effect. Participants were 69 boys and 52 girls of ages 9–14 from Beijing, China. The results indicate that children improve more on the WLT with the combination of instruction and practice than with practice alone (p < .01). The findings depict a relationship between cognitive development and instruction effect on the WLT. |
