Woe unto the administrator who ventures forth into the homework wars. Scale it back, and parents will be at your door complaining about a lack of academic rigor. Dial it up, and you will get an earful from other parents about interference with after-school activities and family time. If you are looking to bolster your particular position with research results, you are in luck, because there are studies that back the more-is-better approach and others that support the less-is-better tack. "Homework has been a hot topic for a number of years now because it affects so many people," says Robert H. Tai, a professor at the University of Virginia's Curry School of Education who has researched the topic and conducted a 2012 study, "When Is Homework Worth the Time?" After studying transcripts and data for more than 18,000 sophomore students nationwide, he found no significant relationship between time spent on homework and grades, but did find a positive relationship between homework and performance on standardized tests. "Homework should act as a place where students practice the skills they've learned in class," Tai says. "It shouldn't be a situation where students spend many hours every night poring over something [new]." This article adds to the discussions on both sides of this on-going issue, and expands it into the international arena. It remains difficult to show causation between increased homework and higher achievement, due to influencing factors such as teacher effectiveness and class participation, researchers say. Most agree that homework should be purposeful, and that more does not translate to better.