From castles and armor to rockets and robots, an object's design relates directly to its purpose. By understanding the purpose of an object, people can create plans for building the object. This fun series guides readers in planning, building, and improving their own cardboard models of castles, roller coasters, and more. Explores how a roller coaster's design helps it fulfill its purpose, and challenges readers to build their own cardboard roller coasters. Vivid photographs and easy-to-read text aid comprehension for early readers. Features include a table of contents, an infographic, a supply list, Think About It critical thinking questions, Making Connections questions, a glossary, and an index. QR codes in the book give readers access to book-specific resources to further their learning. AGES: 8 to 9