To many times a child dsoesn't or is afraid in the classroom because they lack confidence.  They don't feel secure encough to ask a question in fear that they might be looked upon in a negative light.  I like to tell my students that if you aren't sure of something ask about it 9 times out of 10 there are many other students wanting the same question answered, also.  Once you have guided a child not to fear asking and wanting help you are helping them build their confidence which will help them throughout their education and later on when they go out into the world.