American 15-year-olds do about six hours of homework per week, more than kids in most other developed countries. And the amount of homework hasn't changed much since 2003, according to the Organization for Economic Cooperation and Development:

Homework chart: 2003 vs 2012

All that homework, though, might not be helping much. In almost every country in the study, kids who spend more time doing homework also score higher on the math portion of the Programme of International Scholastic Asessment, a standardized test organized by the OECD. But not in the US — doing more homework correlated with slightly lower scores:

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