Problem Solving

Mr Dalziel, our visiting student teacher has been setting us some interesting problem solving challenges. He is encouraging us to keep trying, even when we feel frustrated. Turn the problem around and try it from a different angle. At the moment we are trying to work out what his Granny likes. We know she likes Wellington but not Christchurch. She likes knitting but not sewing and she doubly likes coffee but not tea. I wonder if you can figure out the rule?