Arches and triangles are some of the strongest shapes. Why Arches and Triangles Are Strong introduces the forces that hold them steady and explores how they are used to build sturdy structures. Easytoread text, vivid images, and helpful back matter give readers a clear look at this subject. Features include a table of contents, infographics, a glossary, additional resources, and an index. Aligned to Common Core Standards and correlated to state standards. Kids Core is an imprint of Abdo Publishing, a division of ABDO.