In this day and age, with the development of social networks and electronic transaction, we have been spending a lot of time in front of our computers. For each applications, the users need to sign up and log in. To sign up, we have to provide our information related to Name, age, occupation, hobby, etc, and then the host can collect these data to support their own purposes. In the context of a class, I may introduce the data transmission by asking student to log in an elearning web like Khan Academy or Coursera. By this way, students are required to sign up their accounts. This will lead in my lesson about the data security and help them how to keep their privacy on the cyber space.