This Instructional Activity is a part of the Lesson 29, Unit 4, Grade 6. Students participate in the discussion by answering the teacher's questions and following along in their student materials. For example: The school librarian, Mr. Marker, knows the library has books but wants to reorganize how the books are displayed on the shelves. Mr. Marker needs to know how many fiction, nonfiction, and resource books are in the library. He knows that the library has four times as many fiction books as resource books and half as many nonfiction books as fiction books. If these are the only types of books in the library, how many of each type of book are in the library?