The Important Book by Margaret Wise Brown is an excellent book to help students understand main idea. I've included all the documents I've used this week to teach this book to my 2nd grade students. This includes a main idea poster, lesson idea with chocolate chip cookies, bubble maps, writing templates following the pattern in the book, rough draft paper with writer's checklist, comprehension check on the story, matching game, and many student examples. My students used the concept of this b