I have told the class many times that I am impressed with how they can crank out an opinion piece now, whereas before they weren't sure what to do or how to organize it. We still have some who struggle with remembering an introduction (they just start right in with their reasons), and we still have students struggling with writing more about their reasons (they just copy their box and bullets and make that their opinion piece).
Here are some examples. We started with making a box and bullet organizer in our notebooks for a letter to Mr. Henderson about a change we would like to see made at school. The change could be a serious one or a funny one. I stress to students that they can always just draw a box at the top of the paper and do two bullets whenever they are asked to write an opinion about anything- in science, social studies, or math. It really helps them organize their thoughts and remember parallel structure. After students organized their thoughts into boxes and bullets, they typed their letters or they could chose to hand write it.