Read Why are all bears boys? and then try this with your kids at home or in school. Gather together all of your picture books or children's chapter books and sort them into three piles: 1. Books with a female protagonist; 2. Books with a male protagonist; 3. Books that have a gender neutral protagonist.
What do you notice? Which pile is bigger? What sorts of books are in each pile? Do any discussions stem from what you have found?
You can try the same thing with TV programmes, films, children's magazines etc.