Mi elefante de los mocos

Young readers may have heard about the benefits of using and making the most of their resources, but how does that factor into an economic discussion? This thorough discussion defines resources and describes the different types of resources and why some divide them into three categories and others choose four. The book also addresses the concept of scarcity, showing readers how, because all resources have their limits, it is important to use them responsibly and efficiently in a healthy economy.

Read Along or Enhanced eBook: Take a journey into the wild world of reptiles and amphibians! Readers will learn about crocodiles, lizards, snakes, tortoises, and salamanders. Featuring a glossary, index, colorful images and charts, intriguing facts, and clear, informative text, readers will be sure to be enthralled as they move through this engaging, Spanish-translated book.

Planck consideró como tarea científica suprema la búsqueda de las leyes que rigen el absoluto, el invariante oculto en la realidad externa. Le cupo el privilegio de descubrir uno de esos elementos universales: el quantum de acción, la constante h.

Simple text and photographs introduce the concept of symmetry as displayed by familiar creatures and objects.