In this third volume of the Terra Tempo series, Jenna, Caleb, and Ari join the Academy of Planetary Evolution for a crash course on the evolution of mammals. Using a mighty device (the "Time Orientational Gravitational Gadget for Learning and Educational Resource"), the students travel in time for full-immersion science lessons with their lecturers from the past, including Andrew Carnegie, Annie Montague Alexander, Herman Melville, Winifred Goldring, and more. However, Ari and his friends still must deal with the Treasure Hunters, who seek time maps that will allow their holders to exploit earth's natural resources from all eras. Shapiro packs the story with scientific information about evolution and natural resources, with a strong plea for careful, thoughtful use and conservation of those resources. Herndon's colorful art, including maps and charts, will help readers understand the science while building on an already exciting story. Readers can glean enough information about events in the previous volumes with the introduction and dialogue in the story, so there's no need to start with the first volume.

Gr 3-6 Twins Jenna and Caleb, along with their friend Ari, begin their education at the Academy of Planetary Evolution at the Field Museum of Natural History in Chicago. There they meet fellow geology enthusiasts and brainiacs. With a special device known as a "toggler" the students are able to travel to the times and spaces they are learning about to witness science in real time. Several guest lecturers guide them through their units of study including Andrew Carnegie and Herman Melville. Trouble ensues when Seth, leader of the Treasure Hunters and chief villain of the series, tries to recruit a student for his newest endeavor, REDI (Resource and Energy Development, Inc.) He uses his usual tricks to attempt to achieve his goal, but a great symposium with the greatest minds in science is held to settle the ownership of the time travel maps once and for all. This series is getting stronger with each successive installment and is not only action-packed, but focuses on science in a way that is entertaining, informative, and inspires further research in middle grade readers. Back matter includes several maps showing the migration of the earth's tectonic plates, an equine evolution map, and short biographies for the famous faces that appear in the story. Highly recommended for purchase for school and public library collections. Samantha Lumetta, Public Library of Cincinnati and Hamilton County, OH