Who Knew? The Big Book of Questions That Will Make You Think Again is a 256-page hardcover trivia and facts book by Sarah Herman, published by Portable Press. It brings together more than 130 fascinating articles drawn from the popular Who Knew? series alongside new material, all designed to challenge and expand your understanding of the world.

The book is organized into twelve subject chapters covering weather and climate, the human body, art and architecture, animals and plants, ancient history, food and drink, literature, geography, sports, science, film and theater, and the universe and space. Each chapter ends with a quiz to test your knowledge. Questions explored include topics like whether dogs can smell emotion and how the Incas built Machu Picchu. The book is packed with quirky illustrations and is suitable for curious readers of all ages.