Here's asimple solution:
What your dog is showing is separation anxiety. She's just worried you'll never come back and ditch her. What you'll want to do is correct this behavior because it can get rather annoying. When you come home from school DO NOT give her any attention. No pets, no hi girl, no nothing. Walk straight to your room and close the door. Or stand there, turning your back to her until she calms down. Then when she's finally calm say good girl, give a small treat. Also is she crate trained?