How much television should an 11 year old watch per day?

That depends on whether or not they've done their chores, homework, etc. and when their bedtime is. Make sure to keep in mind that kids should be off electronic devices about 15 minutes or so before they go to bed if possible. The most TV a kid should watch a day is about two and a half to three hours unless they are sick or hurt and can't really do anything else besides watch TV.