Themes: Strange Phenomena, Unsolved Mysteries, Nonfiction, Tween. An alien orb bobs in the sea. Blood seems to spew from a waterfall. Rocks move on their own across the desert. Nobody knows where a radio station comes from. These mysteries keep people guessing. Can they be explained? 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.