Terminating web page after 15 minute

if i were u ...i ll kill the session after 15 min and redirects student to another page as my wish and shows the result hitting db once using his uinque id , and if he want to submit before timer i ll wirte some logic in button click ......no big deal in it,...u r expecting code if so....google it as online quiz app asp ...in codeplex.com u have a very nice example for this scenario