There is separate form which you will get and to be filled from the school and get it signed and school seal from the Principal. Then go to the PRS counter and submit the form while booking the ticket. To avail the Sc/st concession , you must submit a copy of your caste certificate from concerned authorities.
One can book I tickets through IRCTC and later avail the concession from the PRS.(the fare difference deducting the clerkage 20 Rs, will be refunded to the account which is been used for booking)
The...
more... student concession form attached here with.