Final answer:
A teacher points out there's no second chance for a first impression in order to emphasize the importance of making a positive first impression and creating a positive image.
Step-by-step explanation:
In social settings, including school and work, first impressions can be important because they often shape others' initial perceptions of us. The saying 'there's no second chance for a first impression' means that the way we present ourselves initially can have a lasting impact on how others perceive us. If a teacher points this out, they are emphasizing the importance of making a positive first impression in order to establish a good relationship with others and create a positive image.