I agree with waqar.
IMO, childern must be motivated towards & provided opportunities to play different health improving outdoor games (football, cricket, badminton, etc) , instead of watching TV or playing games on computer.
My chidren are school going, and whenever they have done their homework, and it is pleasant outside (especially after Asr prayer), I send them out in a nearby park area. There they can play football or cricket, and can do exercise as well.
On weekends, during vacations and on other days when they are unable to go outside, they generally watch tv for 1-2 hours.