Well you must realize that Bluetooth is short range, about 10 meters. So you would have to be in the same room as the computer that you are transferring. Even WiFi has its distance limitations.
Do you have to code the server side? Do you have any constraints about what can be on the Server.
Personally I think you will find it easier to use HTTP. the Server being a web server with a
Servlet that takes the grades.
Also, I wanted to thank you for asking for advice rather than asking us to do your homework for you.
Mark