I am in the process of teaching my grandma how to use a computer. She has never used a mouse, and to make matters worse, she is used to typewriters with the AZERTY key pattern. She needs a paper (not online) book to help her learn how to use a mac.
Plus I bet she knows what a mouse is and how to use one. Computers have been around since the 1970's and your Grandma has seen them before, even used one or two in her time.