Pequeña historia de la Música

The use of calendars dates back thousands of years. Why are we driven to record time, and what would happen if we did not? Who created the concept of calendars? Why do different cultures use different calendar systems? And why are calendars so important to us? It is about "time" we found out! Created in collaboration with the Smithsonian Institution, this Spanish-translated Smithsonian Informational Text builds reading skills while engaging students' curiosity about STEAM topics through real-world examples. Packed with factoids and informative sidebars, it features a hands-on STEAM challenge...

A foundered Victorian ship looking for the fabled Northwest Passage holds a secret in its icy grave... When Dirk Pitt of NUMAr is almost blown to pieces in a lab explosion, he suspects sabotage. The lab in question belongs to a scientist hoping to use a rare mineral to combat greenhouse gases - but who would want to destroy our one chance to save the planet? However, there are those who will do anything to control such a valuable prize. Pitt's investigations take him to the Arctic in search of a clue to the origins of this precious mineral. There he and NUMAr colleague Al Giordino must battle ...

Presents the things that everyone needs, as well as things some people want, and invites the reader to consider his or her own wants and needs.

Describes the ancient giant kangaroo of Australia's distant past that was five times the size of today's largest kangaroos. Discusses how the animal lived and how it became extinct.