Thank yous are extremely important in the professional environment and you should start learning how to write professional thank yous now. They will come in handy after your graduate school interviews. You can hand write or email them. You should send them out the day of your interview if you are mailing them or the next day by email. These decisions are made promptly so you want to send them out as soon as possible.
Their contact information
Dear interviewer's name,
Thank you for taking the time out of your busy schedule to talk to me about the Physical Therapy Program at Grand Valley State University on Tuesday, October 2, 2014. I appreciate the recommendation that I should shadow more sites before the program begins and I will happily follow up on that. I also enjoyed learning about the department's curriculum, learning opportunities, and why Grand Valley has such a successful program.
I am very interested in the program and hearing from you once the final decisions are made. I am confident that my [volunteer opportunities, experiences and academic successes (be more specific than this)] provide a good fit with your program. Please feel free to contact me at any time if further information is needed. My phone number is (XXX) XXX-XXXX.