You must get your hands on a copy of the book Can I Have a Tyrannosaurus Rex, Dad? Can I? Please! by Lois Grambling.
Why? It's the perfect way to introduce Persuasive Writing.
Even though the worksheets here are aimed at Primary students, I've used it with 4th graders and they loved it just as much as the little ones.
To get more great Freebies visit TheWisestOwl.org teaching blog.