Sacrifice requires that we do things today that don’t have immediate benefits for ourselves; but help others instead. Students have generous hearts but, for the most part, are focused on their own successes and sometimes resist the moral obligation to sacrifice for others.
When students interact with others, they have lots of moral decisions to make. It’s hard for them to decide exactly how to treat other people, especially strangers, since many times they don’t have much information to go on and so they must rely on their intuitive judgements and best guesses. How they decide to act reflects deeply upon their characters.