L.G.
My kids are younger, but my 5 year old loves playing on the computer and watching Netflix on the Wii. What we've done is set up a "pay" system. He gets (poker) chips when he does chores or practices his reading or does worksheets and then each chip is worth 30 minutes of "screen time" - we use a kitchen timer to control it. When the timer goes off, he has the option of paying for another 30 minutes or shutting it off.