Summer vacation is starting for many students and that means many parents are reviewing their television-watching rules.

It turns out their rules matter, a new study says. Children with parents who set consistent rules about watching the tube were less likely to stare at it for more than the one to two hours a day recommended by the American Academy of Pediatrics.

Unfortunately, only roughly half of parents, 49 percent, said they often or very often put limits on how much time their kids spend watching TV, according to the study published online today by Pediatrics,  the journal of the American Academy of Pediatrics. More than a quarter of kids in the study, 27 percent, watched more television than the AAP recommends.

Now the study focused on kids aged 9 to 15 years, but there are lessons for parents who have preschoolers.  (The American Academy of Pediatrics recommends no screen time for kids age two and under.) Perhaps the best lesson from this study is that parents’ rules work.

Our study results suggest that programs that focus on the development of parental limits and that promote physical activity may lead to decreased screen time among youth aged 9 to 15 years. Programs to reduce screen time must address the roles of parents and parental rules, target age, and socioeconomic characteristics of families. Programs might best be focused on educating parents about recommended limits and the importance of consistent rules. – “Influence of Limit-Setting and Participation in Physical Activity on Youth Screen Time.”

The study also said kids who were physically active on sports teams and in other activities were less likely to watch more than the recommended amount of TV.

Poverty Rising: We wrote about the 2010 Child and Youth Well-Being Index report last week, but Early Ed Watch highlighted another key and depressing finding:

“The percentage of children living in “extreme poverty” (50 percent below the poverty line) is projected to climb to 10.1 percent (7.41 million kids) in 2010.” – How the Great Recession is Affecting Kids. 6/14/10.