Middle School Life Science Teacher's Guide is easy to use. The new design features tabbed, loose sheets which come in a stand-up box that fits neatly on a bookshelf. It is divided into units and chapters so that you may use only what you need. Instead of always transporting a large book or binder or box, you may take only the pages you need and place them in a separate binder or folder. Teachers can also share materials. While one is teaching a particular chapter, another may use the same resource material to teach a different chapter. It's simple; it's convenient.