So I walking down the hallway of school and I saw this guy coming in the opposite direction of me. When I saw him, I noticed he kept looking at me (my face in particular) and kept his eyes on me even while I was passing by him. Why did he keep on looking at me when he does not even know me? Usually, guys do not look at me while passing in the hallway but I was surprised when this guy did. If he likes me, then what should I do or say to him the next time I see him?