a skirt, a nice top and cute shoes and be sure to feel confident and comfortable
wear a cute sun dress or a tank and skirt
I suggest something that compliments your figure. Maybe a nice skirt to show of your legs, a button up shirt with a camisole underneath it so that you don't have any unexpected wardrobe malfunctions. Wear some cute shoes, they don't need to be heels (some girls make that mistake) and you should make sure they are both comfortable and they compliment your clothes at the same time. That would work best. If you want to be flirty I think you can pop a couple of buttons down, just for the date, to show a little bit of cleavage and give him something to think about. Something playful like that. Maybe then after you're done you can go back to class and button up.
What do you think?