should kids watch tv?

In my research on "Does TV Affect Kids Behavior" I have discovered that it does and yes is the answer, but now I am trying to see how, and more facts about this topic. So far i was researching how much TV should kids watch a day so parents would be able to know if they want to be aware of it. I was researching and I found a really help full post at kidshealth.org  and in this post there was lots of different answers. it was interesting to learn about this topic. So in my research so far the answer is yes but what I am now coming to is that what about the shows that make you learn how to count and makes you actually learn, (non-violence and is like a school) is that o.k. or does it still affect kids brain sells and it does have an impact on the kids health.