In testing terminology--
Pre-requisite:
(1)Able to speak,listen,sit,move,type,view the computer.(in 
whole must be physically fit)
(2)Must be literate.
(3)Must have minimum general knowledge of life

Testcases:
Action-Tutor must give her brief about computer
Expected:Grandma must get view of how computer must be 
started.

Action:Tutor must then show her how to open connection or 
get connected to internet.
Expected:Grandma must be able to connect to internet next 
time when she starts the computer.

Action-tutor must then guide her to open internet explorer 
by clicking the icon.
Expected:Grandma successfully opens the IE nexttime she 
logs in to system.

Aation:Tutor must check whether grandma is still able to 
consume more knowledge about internet.
Expected:Grandma goes in to disconnect state.And signaling 
cannot be connected.(It means not interested anymore 
invirtual world)

very nice answer no gud ansuer can be given to this question
like testguru has given

Really nice answer......:)