El espacio exterior

Readers won't have to disassemble their favorite toys to discover what makes them work. This book explores electric, magnetic, and motion-powered toys from design to function. It introduces readers to the six simple machines and explains how they use force and motion to do work. Not every toy is a technological marvel. Readers learn about time-honored favorites including the rocking horse, Slinky, and rattles.

Read about the kinds of jobs that people do as engineers, and how they use math, science, and creative thinking to solve problems.

Pocos escritores han tenido una vida tan paradójica como H.P. Lovecraft, el excéntrico y solitario «escritor de espantos» de Providence, considerado por todos como el gran maestro del horror sobrenatural. Sin embargo, Lovecraft murió en el más completo anonimato, sin haber visto editado en vida un volumen de sus narraciones. Fue un misántropo incurable, y sin embargo era apreciado por todos los que le conocieron y se vio rodeado por un círculo de fieles admiradores que lucharon denodadamente para rescatar su obra del olvido. Fue un gran materialista científico enfangado en...

If a person were ever face-to-face with a huge, hungry animal with sharp teeth, they probably wouldn’t care exactly what that animal was! But from a safe location, can we tell whether it was a crocodile or alligator that wanted to take a bite? By examining their jaw structure, teeth, and other physical features, we can easily tell these two animals apart! Graphic organizers and amazing images highlight each animal’s habitat and other small differences between the two fearsome creatures, showing readers just what creature is lurking below the waters.