How Do You Measure Time?

In 1789, George Washington became the first president of the United States. With over 100 black-and- white illustrations, the fascinating story of "the father of our country" comes to life in Spanish - revealing the real man, not just the face on the dollar bill!

This work narrates the meeting of two young students who in a chance chat, begin to play with stars and numbers and learn about physics, chemistry and astronomy. They learn that science is in everyday life so that we imagine it is not a restricted area, only for the geniuses, but a tool, a way of life, a passion.

People today refer to the Midwestern and prairie states as flyover country. During the Civil War, crossing those areas was the biggest obstacle in uniting the East and West Coasts of our divided nation. An act of Congress in 1862 authorized the Central Pacific and the Union Pacific railroad companies to build a railroad that would link the coasts. Seven years later, on May 10, 1869, an overwhelmingly immigrant labor force completed the task when a rail line was join in Promontory, Utah. The states had become united at last.

Con páginas desplegables y atractivos modelos realistas de las especies de dinosaurios más populares, este libro es una maravillosa introducción al mundo de estas fascinantes criaturas. With foldout pages and beautiful, realistic models of the most popular dinosaur species, this book is an incredible introduction to the world of these fascinating creatures.