Bullfrog Books

What's the biggest bird? Is a blue whale bigger than an elephant? What's the tallest animal? In Biggest Animals, beginning readers are introduced to the largest animals across a variety of… More →

How much weight can an elephant carry? What animal has the strongest bite? In Strongest Animals, beginning readers are introduced to the strongest animals across a variety of classes and… More →

In Cardinals, beginning readers will learn how these bright red birds defend their nest, find food, build nests, and raise their young. Vibrant, full-color photos and carefully leveled text… More →

In Stinky Animals, readers will learn about smelly animals, including stink bugs, skunks, and musk oxen. A comprehensive Why Are Some Animals Stinky? back matter feature highlights… More →

What animals use tools? How do orcas work together to hunt? Can elephants tell when a friend is sad? In Smartest Animals, beginning readers are introduced to the smartest animals across a… More →

In Quails, beginning readers will learn how these birds follow each other, find food, build nests, and raise their young. Vibrant, full-color photos and carefully leveled text will engage… More →

In Gross Animal Eaters, readers will learn about different bizarre animal diets, including dung eaters, blood drinkers, and body-munching parasites. A comprehensive Gross Animal Foods… More →

What animals use tools? How do orcas work together to hunt? Can elephants tell when a friend is sad? In Smartest Animals, beginning readers are introduced to the smartest animals across a… More →

What's slower than a sloth? Could you beat a tortoise in a race? What's the slowest swimmer? In Slowest Animals, beginning readers are introduced to the slowest animals across a variety of… More →

In Flowers, beginning readers will learn to identify different kinds of flowers. Photos and carefully leveled text provide defining details for each kind, such as petal color, kinds of stems, More →

In Referees and Umpires, beginning readers will learn what referees and umpires do and how they enforce rules and keep sports fair. Carefully leveled text and action-packed photos show how… More →

In Trees, beginning readers will learn to identify different kinds of trees by their leaves, bark, nuts, and fruits. Photos, labels, and carefully leveled text provide defining details for… More →