Themes: Strange Phenomena, Unsolved Mysteries, Nonfiction, Tween, Emergent Reader, Chapter Book, Hi-Lo, Hi-Lo Books, Hi-Lo Solutions, High-Low Books, Hi-Low Books, ELL, EL, ESL, Struggling Learner, Struggling Reader, Special Education, SPED, Newcomers, Reading, Learning, Education, Educational, Educational Books. 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?Engage your most struggling readers in grades 4-7 with Red Rhino Nonfiction! This new series features high-interest topics in every content area. Visually appealing full-color photographs and illustrations, fun facts, and short chapters keep emerging readers focused. Written at a 1.5-1.9 readability level, these books include pre-reading comprehension questions and a 20-word glossary for comprehension support.