Most Helpful Guy
Just text him if you're superb shy. If he knows what he's doing. He will ask you out if he genuinely likes you1THIS IS NOT RELEVANT ANYMORE
Most Helpful Girl
I had this problem in high school too. Start small with just a smile and "hey" every time you pass him. Making eye contact helps.
When you start to feel a little more comfortable, plan a few possible things to chat about (casual things) in advance. Then just try to remember he's a (nice) guy who has invited you to talk to him. You're not doing anything wrong or embarrassing; you're just being nice back and being yourself.
He might even approach you first if he's sees you're approachable again from the smiles.
You can do it! :)1THIS IS NOT RELEVANT ANYMORE