Heroes y villanos / Heroes and villains

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.

El carácter de Kolmogórov se forjó en una época de revoluciones sociales y guerras mundiales. Vivió el estalinismo, la posterior rectificación de errores y el inmovilismo que luego daría paso a la perestroika. Aunque siempre se consideró a sí mismo un matemático puro, una parte esencial de su obra fueron sus investigaciones aplicadas a otras ciencias. Sus esfuerzos estaban regidos por una idea clara - discernir las diferencias y similitudes entre orden y caos. Mucho más que cualquier otro matemático, amplió los dominios y la comprensión humana del azar. Reinó en una escuela...

Introduce students to the scientific method with this Spanish science reader that features easy-to-read text. This book teaches important scientific topics and vocabulary terms including hypothesis, data, experiment, conclusion, method, research, and more. Nonfiction text features include a glossary, index, and detailed images to facilitate close reading and help students connect back to the text. Aligned to state and national standards, the book also includes a fun and engaging science experiment to develop critical thinking and help students practice what they have learned.

¡Conoce al iguanodon, un dinosaurio herbívoro que pesaba toneladas literalmente! Las imágenes coloridas ayudan a los lectores a aprender cómo era la vida para estos comedores de plantas de punta. Meet the iguanodon, an herbivore dinosaur who weighed tons—literally! Now in Spanish, carefully leveled text and colorful images help readers learn what life was like for these spiky-thumbed plant-eaters.