Opinion Writing is tricky for littles ones. They all have opinions, but supporting their opinions with reasons requires support.
After studying healthy eating, we used this brainstorming sheet and planning sheet to produce a well-supported piece explaining why they had the healthiest meal. It leads to some wonderful dialogue about what was actually healthy vs. what seemed healthy, as well as being an authentic topic to practice the skills of Opinion Writing.
It includes a themed sheet for writing their final drafts and a teacher rubric.