We study the effects of enrichment activities such as reading, homework, and extracurricular lessons on children’s cognitive and non-cognitive skills. We take into consideration the opportunity cost of spending time on enrichment, as it may replace activities such as sleep and socializing. Our study controls for selection on unobservables using a control function approach that leverages the fact that many children spend zero hours per week on enrichment activities. At zero enrichment, confounders vary but enrichment does not, giving us direct information about the effect of confounders on skills. Using time diary data available in the Panel Study of Income Dynamics (PSID), we find that the net effect of the last hour of enrichment is close to zero for cognitive skills and negative for non-cognitive skills. The negative effects for non-cognitive skills are concentrated in high school, consistent with elevated academic pressure related to college admissions.

我们研究阅读、家庭作业和课外课程等丰富活动对儿童认知和非认知技能的影响。我们考虑了花时间丰富自己的机会成本，因为它可能会取代睡眠和社交等活动。我们的研究使用控制函数方法来控制对不可观察量的选择，该方法利用了许多孩子每周花在强化活动上的时间为零的事实。在零丰富度下，混杂因素会发生变化，但丰富度不会变化，这为我们提供了有关混杂因素对技能影响的直接信息。使用收入动态小组研究 (PSID) 中提供的时间日记数据，我们发现最后一小时的充实对认知技能的净效应接近于零，对非认知技能的净效应为负。非认知技能的负面影响集中在高中，这与大学招生相关的学业压力增加是一致的。