A hippo's mouth is huge, measuring about four feet (1.2 m) from top to bottom when open. That's big enough for a six-year-old kid to fit inside! These big mouths make a lot of noise. Hippos can produce a 115-decibel roar that's as loud as a train engine. They also make softer noises such as croaks, clicks, and bellows that are heard in the air and underwater at the same time--something no other mammal can do. These are just some of the interesting facts kids will discover about these noisy giants. Spectacular photos and clear, easy-to-read text will engage emergent readers as they discover where hippos live, how they stay safe, and the different ways they communicate with each other. Kids will also learn the origin of the name hippopotamus, which is Greek for "River Horse"--and discover why this name is actually inaccurate. A "Sound Check" chart at the end of the book compares the decibel level of a hippo to familiar noises, including an ambulance, a lawnmower, and a train engine.