This writing exercise pairs with a prompt asking students to write a letter to their school superintendent, giving him/her one piece of advice. The students are required to develop reasons supporting why s/he should take their advice, as well as creating a convincing counter argument to an objection s/he may have. In the case of the eighth graders at my [former] school, they actually send these letters to our superintendent who reads them and creates a video, responding to a few popular pieces of advice. He also selects a few students to read their letters before the school board. It's a terrific authentic writing opportunity if feasible.
However, it may also stand alone as a powerful practice activity if your schedule does not allow for the addition of a new writing prompt.