The family sphere(范围) used to be defined by its isolation from the public realm. There was the public male realm（领域）of "rational accomplishment" and cruel competition, and the private female and child-rearing sphere of home, intuition（直觉）and emotion. The private realm was supposed to be isolated from the realities of adult life. For both better and worse, television and other electronic media tend to break down the difference between those two worlds. The membrane around the family sphere is much more permeable(可渗透的). TV takes public events and transforms them into dramas that are played out in the privacy of our living rooms, kitchens and bedrooms.
Parents used to be the channel through which children learned about the outside world. They could decide what to tell their children and when to tell it to them. Since children learn to read in stages, books provide a kind of natural screening process, where adults can decide what to tell and not tell children of different reading abilities. Television destroyed the system that separated adult from child knowledge and separated information into year-by-year slices for children of different ages. Instead, it presents the same information directly to children of all ages, without going through adult filters.
So television presents a real challenge to adults. While a parent can read a newspaper without sharing it with children in the same room, television is accessible to everyone in that space. And unlike books, television doesn't allow us to flip（翻转）through it and see what's coming up. We may think we're giving our children a lesson in science by having them watch the Challenger take off, and then suddenly they learn about death, disaster and adult mistakes.
Books allow adults to discuss privately what to tell or not tell children. This also allows parents to keep adult material secret from children and keep their secret keeping secret. Take that same material and put it on The Today Show and you have 800,000 children hearing the very things the adults are trying to keep from them. "Television takes our kids across the globe before parents give them permission to cross the street."
More importantly, children gradually learn that adults are worried and anxious about being parents. Actually, television has also places families under a lot of stress.
How Television Changes Childhood?

Main comparisons	Contexts
Distance between ___and the outside.	Homes used to be isolated from the ______realm.
Homes nowadays are ___to the outside world.
Media through which children can obtain information	In the past, children might learn ____about the outside world with the help of parents and ______.
More information is got directly through TV and other electronic media, which breaks down the _____ between adult world and the child world.
______ of the information children get	Traditionally, kids could only knew what they should learn at their age, carefully_____by their parents.
Everything can possibly be known by children, including many aspects of ____ life.
Effects  on family education
Parental instruction	Families are now under greater stress than before.   Adults are anxious about being parents and faced with   new _______.