Narwhals are often called the "unicorns of the sea." But these fascinating creatures are members of the whale family. Read all about narwhals as you practice addition. This nonfiction math book combines math and reading skills, and uses real-life examples of problem solving to teach subject-area content. The dynamic images, detailed sidebars, practice problems, and math diagrams make learning addition easy and fun. Text features include a table of contents, a glossary, an index, and captions to build vocabulary and increase understanding of math and reading concepts. An in-depth problem-solving section provides additional learning and practice opportunities. Engage students with this high-interest math book