Did you ever write a tale together with your kid?
I am a firm believer in learning-by-doing approach. There are different good ways to get your kid learn writing. And here is another good one. Take a look at this little story:
Once upon a time there lived a little dog. He was bought for a nice pretty girl for a St. Valentine's Day and lied on a computer mini-tower watching its masters living in a big old fashion room. It was a fat white dog with long brown ears and big brown stain on its back. The dog didn't know anything except the store's shelf where he lived for a while, and this mostly dark room where he lied alone. No wonder, since he was bough and brought here in a rosy paper packet along with a card and dry flowers in a shell.
"What a beautiful bouquet!" the dog was thinking while sitting in the paper bag and looking at the stars in the sky. Finally, he was given to a girl and laid on a computer.
The only thing he was dreaming about is living an adventurous life and see the world. He knew that some day he will do this, but it was impossible right now.
It might last years after years, but one sunny day someone has entered the room. The dog was just sleeping, so it didn't noticed it until it opened its eyes and saw...
You can read it to your kid and ask him/her to imagine a bit of sequel. And then you both publish it on the story page. You may add different sequels, and ask your friends to do the same until you have a big multi-path storygame, which can be played by you and your kid. And what's the best, your child will know that he is a co-author of something big.
Here is a link that might be useful: A Shaggy Dog and a Big Adventure