Moving Heavy Things is one of the top "Young Adult" (JR High School and up) books in each of several subcategories of Amazon's "Books > Children's Books > Science, Nature & How It Works" hierarchy. The simple, yet to the point title has the classic feel of a children's "how to" book, yet the book is far from fluff.
The focus is on simple mechanics, and manages to cover a broad range of concepts through explanation and illustration rather than with discussions of vectors, equations and complex formulas. Without mentioning terms such as kinematics or dynamics, it gives readers a feel for what the real life effects of weight distribution, centering, friction, pulleys, and wedges are on moving day to day objects of the larger varieties.
It covers everything from block and tackle to enough different knots to impress a Boy Scout. Some of it might be too advanced for many pre-teens, but even older teens and "young adults" might consider it a fun casual read. It's not meant to be a scientific or field manual in any literal sense, but even a non technical adult might be able to walk away with a better understanding of the world because of it. It's not completely free of formulas or calculations either, but a solid foundation of arithmetic is all that should be needed to make sense of them.