It sounds quite alarming that 8-18 year olds on average spend about 7.5 hours a day on entertainment media (that includes cell phone, TV, Music players and computers). But considering the fact that some of those devices being an integral part of our lives (like cell phones), use of them for entertainment may be over quoted.
A national survey by the Kaiser Family Foundation found that with technology allowing nearly 24-hour media access as children and teens go about their daily lives, the amount of time young people spend with entertainment media has risen dramatically, especially among minority youth.
Today, 8-18 year-olds devote an average of 7 hours and 38 minutes (7:38) to using entertainment media across a typical day (more than 53 hours a week). And because they spend so much of that time 'media multitasking' (using more than one medium at a time), they actually manage to pack a total of 10 hours and 45 minutes (10:45) worth of media content into those 7½ hours.
Also quoting from the survey, the same set of people surveyed say that about 55% of people are scoring B+ (mostly As or Bs + mostly As) grades in school. That definitely has something to say about how the new generation is using those gadgets.