People have been sending mail for a long time. But how they do it has changed a lot! Read about the history of mail as you learn to collect data. This Spanish 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 data measurement 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 nonfiction book!