First and foremost, being around new people causes anxiety. New people mean new languages, new faces, new attitudes etc. Compared to adults teenagers are less exposed to people of different backgrounds and cultures. It is natural to feel uncomfortable when you are conversing in an unfamiliar language. Therefore choosing to remain silent seems like a better option to those who fear that they might sound silly.
Furthermore, teenagers feel insecure when being thrown into a sea of people with a variety of talents. The number of students in colleges and universities is far larger than high schools thus more talents are gathered within a institution. Some teenagers might be intimidated by people who are more outspoken and may seem to be more intelligent. Hence they start doubting themselves and it can be frustrating for those who cannot keep up with the rest. Consequently teenagers hold back from participating in any activity, including tutorial discussions.
Lastly, teenagers have to fend for themselves in a college or university environment which may lead to the cause of uncertainties. Unlike teachers, lecturers do not provide as much help to students when they assign students homework or when explaining a certain topic. It is expected of students to do their own research to find for answers. Those who have been “spoon fed” by their teachers in the past will find it difficult to be independent as there is a drastic change in the learning system. As a result they tend to feel helpless, confused