El ciclo del nitrógeno (The Nitrogen Cycle)

Defines screws, explains their functions, and suggests simple experiments to demonstrate how they work.

Recounts, in Spanish and in English, the story of Ricardo Romo, a Hispanic-American All-American athlete and scholar who became, among other things, a U.S. representative to the United Nations, and the president of University of Texas at San Antonio.

As a land that’s constantly in flux, Earth sometimes reveals clues about the plants, animals, and other organisms that lived long ago. Fossils teach us much about what life was like millions of years ago, answering the questions of how Earth changed and maybe even why it changed. This essential Earth science topic is thoroughly explained through manageable text, fact boxes, informational charts and diagrams, and a glossary and index. Readers will become young Earth detectives by the time they’re through with this text!

Clues about the lion's physical characteristics, behavior, and habitat lead the reader to guess what animal is being described. Presented in English and Spanish. Presented in English and Spanish.