[header] How to tell if a girl has a crush on you [title] Try to catch her staring at you. [step] This one is a giveaway. If you look across the room in class or at a party and catch her looking right at you, then she may have a crush on you. 
If she sees that you've noticed her staring and looks away and blushes, or gives you a little smile, then she may be acknowledging that she may like you. [substeps] Just don't be too obvious about trying to catch her staring at you, or she may think that you're the one staring at her.