In this video, the teacher explains how to write a closing paragraph that stays on topic for a writing prompt. The teacher emphasizes the importance of referring back to the prompt and the main ideas of the response. They provide clear steps for writing a good closing paragraph, including rewriting the thesis statement, summarizing the supporting details, and ending with a strong sentence that highlights the importance of the idea. The teacher also reminds students to consider the reader and use the hook from the opening paragraph to craft a compelling ending.