La optimización mecánica en el medio acuático

Describes where fossil fuels come from, their uses and forms, the harm they cause to the environment, and sources of renewable energy.

The need for speed is the motivating factor in this engaging, Spanish book. Readers learn the history of travel from the very slow to the supersonic and beyond, including everything in between. They learn and discover the factors that influence motion for all types of vehicles: land, air, and water alike. They also learn different ways to measure speed and read about energy uses for different vehicles. With greater speed comes greater risk. Readers learn how engineers are always seeking new and better ways to keep people safe as they travel faster and go farther.

Esta historia cuenta cómo un niño, sin quererlo, sube a un cuadrilátero: sólo que el combate no será máscara contra cabellera, como los que tanto disfruta en los espectáculos deportivos. Tendrá que pelear con toda su fuerza interior para sanar de leucemia, un viejo y mañoso adversario.

Did you know that the president doesn't just work in the White House, he also lives there? Or that the first White House was burned down by the British in the War of 1812? Take a tour through this beautiful house and discover how it has changed over the past two hundred years in The White House.