Big Idea: Forces and Structures is an expository text organized in three chapters covering structures, forces, and building structures. Each two-page spread is linked to a big idea, such as “Forces push and pull on all structures.” Each chapter concludes with an experiment written in procedural language, and a final experiment challenges students to “think like an engineer.” Each two-page spread follows a predictable format: Big Idea, section heading, labeled photographs, comprehension questions. The inside front cover offers a handy list of key terms in each chapter. A contents, glossary, and index are provided. Sentences are short and simple in structure. Everyday language is used to explain science concepts. Content words are defined in words, photographs, and diagrams. This title is from the Big Idea series. Explore the big ideas of Science and Social Studies and promote simultaneous language development and content acquisition.