NOT saying hi

So I recently have had this awkward thing where I will not say hi to my teacher guy. I'm not sure why...I feel awkward not saying hi, but somehow ingrained in me is to not interrupt and thus it seems super awkward to just stand there and wait for them to notice you just to say hi...thus I have nullified the whole "greeting" situation by completely ignoring it. It worked successfully tonight on not greeting him at a social (opps)...I just fear this new outlook of a greeting will not be perceived as unfriendly or sociopathic, I'd prefer if it was just awkward. Perhaps I'll have to invent another way to greet...hmmm...any thoughts?