Themes: Biological Weapons, History, Nonfiction, Tween. Bioweapons have been used throughout history. They are made from things in nature and are used to kill. Find out about several common germs and how they have been used as bioweapons. Red Rhino Books Nonfiction is the first Hi-Lo children's nonfiction series at a first-grade reading level for students in grades 4–7. Visually appealing fullcolor photographs and illustrations—along with fun fact boxes—keep these books flowing. Also includes prereading comprehension questions along with a 20-word glossary for further reading support.