Nora Roman 
Cómo utilizar una báscula (Using a Scale) [PDF ebook] 

We use scales more than we might notice in our daily lives. We weigh our food at stores, weigh our packages at the post office, and even weigh ourselves. Scientists use scales for important experiments, too. In this essential introduction to this super science tool, future scientists will learn about different kinds of scales. They’ll learn how to use scales to investigate objects in their everyday lives and come to appreciate how this often-used instrument helps us in so many ways.