Are you supposed to look at people when you go through a hallway for a brief second?

for example at school i don’t look at anybody in the hallways i just walk forward to my class because looking at other people makes me nervous, but when I go to school early in the morning there might be one person who is walking in my direction to go somewhere when they briefly look at me and then look away. Are you supposed to do that? And if you do it are you supposed to smile a little in order to seem polite or do you just look at them and walk away? its very confusing