Themes: Area 51, Secret Projects, 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. There is a United States Air Force base in the Nevada desert once so secret it never appeared on maps and was rumored to house alien spaceships. 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.