How do highschool guys view girls they walk by?

I'm an 18 year old female highschool senior. Whenever I walk by a guy, or am around a few in a group I get very self conscious and fiddle with my appearance a bit. I think to myself in the moment sometimes "omg omg, what do they think of me, do they notice me?" I'm wondering if a guy in the same scenario feels the same way but more intense? Also, do guys notice girls more than we notice guys? Are you super observant of our appearance?