I think it is a matter of finding out what is this child's interests.  Sometimes a child is most interested in activities that are not large groups and not always school sponsored.  Our daughter found her niche in acting and working with dogs at a rescue. She took small acting classes and also some summer camps that helped her to learn the behind the camera work of television.  Also, we fostered dogs in our home and then went to small dog adoption shows where she could proudly show off the dog she had helped take care of and "screen" the people she thought would be best to "parent" the dog.  Neither were through the school and involved a small group of people.  She now is a young adult and handles bigger groups excellently.

To encourage a shy child you should encourage him/her for the activity or tell him/her about it's benefits .

I have similar problem. My son 3 yrs old very shy to face people. Even if we say some positve words for his good work he feel ashamed. He has learned many things like counting, alphabets, colors etc but he is very hesitant to repeat these in front of people. What should i do to bring confidence in him?