Lágrimas de cristal

Wind Power: A waving flag, blowing leaves, a kite soaring through the skyall are moved by wind power. Wind is also our fast-growing source of energy. Find out how wind forms and the different ways we may use it in the future.

Until just over 150 years ago, northern Mexico extended thousands of kilometers farther than its current border with the United States. Many different indigenous groups flourished in that region before the Conquistadors arrived. What we know about their lives and customs is the result of archeological discoveries and the chronicles of the first Spanish priests and soldiers that had contact with them.

¿Existen los fantasmas? ¡Viaja al sur de Estados Unidos y deci ́delo tu ́! Explora la cueva Bell Witch, pase ́ate por el sanatorio Waverly Hills y visita El A ́lamo. ¡Te espera una aventura espeluznante!

Examines the nature of inclined planes and wedges, how they can reduce the amount of force necessary to perform work, and ways in which they are used.