A compendious and stunningly illustrated fact-filled book for children who have endless questions about how the world works. How do scientists see into space? How do polar bears keep warm? How do keys open locks? How do fireworks explode? Featuring more than 150 compelling questions about space, Earth, machines, buildings, animals, and the human body, this magnificent book by the author-and-illustrator team behind the bestselling First Big Book of Why provides answers for every inquisitive child. And these are answers you can trust, as they have all been thoroughly fact-checked and reviewed by subject experts, who are proudly profiled in the book.By encouraging children to question how things are happening in the world around them First Big Book of How supports STEAM learning and nurtures curious minds. The warm and playful text is accompanied by stunning real-life photography as well as gorgeous original illustrations and helpful, friendly diagrams. This book is the ultimate gift for kids who need to know everything--and now!Includes a contents page, glossary, index and source notes.