Agujeros negros (Black Holes)

For many years, people believed there were nine planets that orbited the sun. Now we say there are eight. What happened to the ninth planet, Pluto? What are the different planets like? What exactly makes a planet a planet? These are the many intriguing questions answered with this high-interest book, crafted to be accessible for readers of all levels. Young astronomers will be especially fascinated by the stunning photographs and the "Make the Grade" fact boxes.

Describes the importance of farms and the changes that have taken place on farms in the United States from the eighteenth century to the twentieth century.

Bitácora es un nuevo curso de español basado en el Marco común europeo de referencia y en el Plan curricular del Instituto Cervantes. El manual propone unidades construidas a partir de documentos variados y estructuradas en torno a tareas de aprendizaje y tareas de comunicación. El léxico cobra un protagonismo especial y se integran coherentemente las nuevas teconologías.

Readers will learn about the important relationship between producers and consumers as well as buyers and sellers and how they all work together to create a healthy economy. This instructive volume defines basic economic concepts like goods and services and explains production with examples of the different types of production. It also covers the primary and secondary industries that produce goods. Concepts such as marketing and advertising are also covered, for a well-rounded view of this fascinating aspect of the economy.

El libro del pan (The Bread Book) helps Spanish readers strengthen their multiplication, division, and fractions skills while learning interesting facts about bread. Students will learn about wheat grain, nutrition, and bakeries with this nonfiction math reader. This classroom resource includes a glossary, engaging images, mathematical diagrams, and a fun historic timeline of bread to help students develop their math and reading skills.