Effects of Study Load on Science Achievement: Searching for a Turning Point with Multilevel Piecewise Regression.

With an educational issue that has caught the attention of many countries in the world (study load), a population of 8th graders from a typical Chinese metropolitan city (40,536 from 118 schools), and an advanced statistical strategy (multilevel piecewise regression), we examined whether there was a turning point in terms of the effects of study load on science achievement. We did identify a turning point for each and every measure of study load. For weekday learning on science achievement, we identified a turning point of 22.50 hr for the effects of in-school learning, 7.50 hr for the effects of homework, and 12 hr for the effects of after-school learning. For weekend learning on science achievement, we identified a turning point of 1.50 hr for the effects of in-school learning, 5 hr for the effects of homework, and 1 hr for the effects of after-school learning. In each case, the difference in effects before and after the turning point was statistically significant, indicating that the effects of study load on science achievement were nonlinear. All of these turning points offered important implications for science education.