¿Por qué hibernan los animales? (Why Animals Hibernate)

Diamonds and salt are both minerals, but diamonds are more rare than salt. Curious readers will learn what physical and chemical conditions must be present for minerals to form. They'll discover how minerals are identified and how they are used in daily life. Informative and interesting text presents readers with this science content in a fun way. A graphic organizer shows how different minerals are identified and fact boxes provide readers with exciting supplementary information.

When rocks change because of environmental conditions, the new rocks are called metamorphic rocks. A rock's chemical or physical makeup may change because of conditions such as temperature, stress, or pressure. Your readers will learn fascinating facts including where metamorphic rocks are most commonly found, the different types of metamorphism, and how metamorphic rocks are identified. Full-color photographs depict these rocks in nature. A helpful graphic organizer shows how these fascinating rocks form.

52 actividades para talleres de poesía infantil agrupados en tres capítulos: 1. Poesís oral y floclore. 2. Juegos con poemas. 3. Un cuento en verso: La Bruja Pimienta.

Esta cuarta edición expone los fundamentos de las señales y sistemas discretos en el tiempo y procesamiento digital de señales. Este texto es adecuado para estudiantes de Ingeniería eléctrica, ingeniería informática y Ciencia de la computación.

In 1846, travelers heading for California became trapped high in the mountains of the Sierra Nevada. Snowdrifts surrounded their shelters, and food supplies dwindled. How they stayed alive remains one of the most gruesome stories in US history. However, some facts that have come to light recently through archaeological digs will surprise even those who think they know the story. This gripping book, including maps and images of the era, tells the true account of the doomed Donner party.

Susana, una niña española que padece anorexia, se traslada una temporada al campo con sus abuelos; allí conoce a Nicoleta, una niña rumana cuyos padres han llegado aquí en busca de trabajo. Dos maneras de ver el mundo y de afrontar la realidad totalmente diferentes que, lejos de provocar enfrentamientos, llegan a entenderse y a ayudarse. En esta ocasión, nuestra joven autora nos ha planteado una situación real como la vida misma que ha tratado con una humanidad y una delicadeza especiales; la amistad y la confianza en los demás se ganan paso poco a poco para solucionar los problemas a ...