Cómo ser adolescente y ser felíz en el intento

What causes sound? How does sound travel? Sound begins when matter vibrates. Without this vibration sound could not move and nothing would make any noise. Starting with tiny molecules, this book explains the main concepts of sound and furthers understanding through a series of easy-to-do experiments that will appeal to readers of all ages.

Readers are introduced to some of the most well-known criminals and tyrants of the past in this exciting nonfiction reader. Featuring intriguing facts and theories, colorful images, and informational text in conjunction with a glossary of terms, a bibliography, and a list of helpful websites with more information, this text will make readers want to learn all they can about ancient history and the bad guys and gals from the past. This book has been translated into Spanish.

Las vidas del Dr. Bethune complementa otras muchas investigaciones previas llevadas a cabo tanto por los Stewart como, en el caso español, por Jesús Majada, comisario de la exposición La carretera Málaga-Almería, visitada por casi cinco mil personas en la Universidad de Salamanca en octubre de 2006. En palabras del profesor Rodríguez Celada, director de la colección editorial “Armas y Letras” y autor del prólogo, nadie podía permanecer indiferente ante “el genio extemporáneo, el líder indiscutible, el adalid temerario, el jefe autoritario, el paladín romántico, un ser...

A simple biography of the naturalist who founded the Sierra Club and was influential in establishing the national park system.