Microphone

My small girl talks quite soft in school. Sometimes I wonder did her friends can listen what she said or not. I guess she also talk softly to her teachers too. Therefore I remind her constantly to talk louder a bit in school coz at home her voice is very loud. But she replied me that her teacher will angry if she talks louder in class. I think this is just an excuse for her. I told her if everyone cannot hear what you said, next time they may ask you use a microphone to speak to them!