Agujeros negros (Black Holes)

Esta es una colección de pequeños alienígenas guardianes de la naturaleza que salen de su planeta en la búsqueda de la mayor contaminador del universo, el malvado Zirt Zlunder. Se escapa y viene a parar en la Tierra. En este libro Zirt Zlunder el contaminador está contaminando el Ártico, donde se escondió. Los Pequeños Guardianes Ellos encuentran Zirt Zlunder e impedirán que contaminen el Ártico. ¿Tendrán éxito? ¿Deberán arrestar a Zirt Zlunder el terrible contaminador?

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

Readers may never expect that they might free fall to Earth, but if they have ever dived into a pool, that's exactly what they've done. This book shows readers how Newton's three laws of motion affect divers, skydivers, and mountain climbers' movements. Readers discover who uses gravity, and who works against it, and all other forces that contribute to a successful dive or climb. After reading this book, readers can decide if they will ever be interested in engaging in one of these extreme sports.

This book has been created with the intention of reconnecting with the ancient Mesoamerican civilization known today as Aztecs, and their language, while also cultivating both English and Spanish.