To make curls work at this mid length, hair is curled tighter to fit in as many coils as possible. Second, to maintain length, the curls start around the chin (with an extra twist to frame the face).
So if you have medium hair, absolutely wear it curled and down for prom! You can even style it yourself!
Start with a blow out with some volumizing spray, like It’s a 10 Miracle Blow Dry Volumizer or Bio Ionic Bodifying Blow Dry Spray. Then grab an easy to use curling iron, like the Remington Curling Wand for maximum control.
Starting at the front, curl hair away from the face in 1-2 inch sections. It’s up to you if you want to curl your whole head or just the top layer of hair.