IMO a book on the principles of design is a must to have. There are hundreds online to buy and I think great for kids to actually use something besides the computer . I still love to sit down at my drafting table with a nice sharp pencil and a clear piece of paper to do my designs. Yes there are tons of different software and I do use some for clients that have a hard time to visualize some big changes. Get her a good book on the principles and then sit down and figure what she is really interested in, is is decorating or actual designing of space. I have to admit the whole decorating part is not my favorite but I love making spaces function better .