Freedom of speech is the basic right of individual. The first amendment protect individual`s right of free speech based on their religious or political beliefs. The point is that individual may express their “dissent opinion”, which refer to “offensive” and “disruptive”. Moreover, some people may abuse their right to express ”hate speech.” Thus, we need to think in different perspectives before we express our opinion avoiding disruptive other people`s right. The limitation of free speech involves the its audience and the speaker itself. There is a difference standpoint between speaker and audience. For audience, what kind of speech is appropriate for different groups of audience, especially for special groups, such as children, women, different race and special interests? The speech open to children is controversial topics among education field, especially sexual topic. How much should children know and how deep they should know? In my opinion, in terms of sexual topic, what children need to know is enough for children to protect themselves. The limitation should depend on the content of speech. Children is the vulnerable groups in our society, people have the obligation to protect them, especially their teacher. Also teacher have the duty to let them how to protect themselves. Another special group is female, who are the vulnerable group in our society as children. Thus we do not sure whether audience could totally understand what speaker what to express. Moreover, some people who stand in extreme point may use the opinion to get their own purpose, which may damage other people`s right. Thus before we express our own opinion, we should think more than individual point of view, which concern more about the social reaction. Thus we can make more appropriate speech in public.