With its long neck and front legs, Brachiosaurus was the giraffe of the prehistoric world - a giant giraffe. Readers learn about this huge plant eater and its Jurassic home from carefully leveled and engaging text, bold illustrations, and interesting facts reviewed by Smithsonian experts.

The fierce and deadly sabertooth cat pounced on its prey during the Ice Age. Readers learn about this prehistoric predator from engaging, carefully leveled text and bold illustrations reviewed by Smithsonian experts.

Scientists estimate that there are 8.7 billion animal species on the planet. There are about 400,000 plant species. New plants and animals are being discovered every day. Scientists who study these species have lots of choices to make and lots to learn. Now the choice is yours. Would you rather be covered in feathers or scales? Would you want to be an oak tree or a giant water lily? Would you choose to talk to animals or understand plants? It's your turn to pick this or that!

Scientists estimate that there are 8.7 billion animal species on the planet. There are about 400,000 plant species. New plants and animals are being discovered every day. Scientists who study these species have lots of choices to make and lots to learn. Now the choice is yours. Would you rather be covered in feathers or scales? Would you want to be an oak tree or a giant water lily? Would you choose to talk to animals or understand plants? It's your turn to pick this or that!

The human body is amazing. Your blood makes up about 8% of your body weight. On average, your heart will beat more than 3 billion times in your lifetime! Doctors and scientists make choices every day about how to keep our bodies going. But what would you change if you could? Would you choose to have super strength or super speed? Would you rather have no bones or no muscles? It's your turn to pick this or that!