In this video, the teacher explains how writers use each sentence to provide new information to their readers. They use the example of writing about sharks to illustrate the concept of paragraphs and grouping related information. The teacher emphasizes the importance of avoiding repetition and ensuring that each sentence informs the reader. They guide the students through revising their own writing to eliminate repetitive sentences and make their paragraphs more informative. Overall, the video teaches students how to effectively structure their writing and provide new and interesting information to their readers.