T. H. Baer 
Medir el peso (Measuring Weight) [PDF ebook] 

It’s usually rude to ask how much someone weighs, but in science it’s an important thing to know! Readers learn how to measure weight in a variety of different ways, from ounces or grams used for small measurements, pounds or kilograms used to measure people, and tons and metric tons we used to measure larger loads. Using simple text to explain scientific and engineering principles fulfills STEM course requirements in a fun and engaging way and colorful photographs and graphics make the content even more accessible.