Libros de Sally M. Walker (2 libros)

What is work? You may think work is doing chores or going to a job, but you do work every time you move something from one place to another. With experiments that demonstrate these fundamental concepts, discover how you work, and how simple machines make doing work easier.

What is matter and where can it be found? Everything in the world is made of matter, whether it is a solid, a liquid, or a gas. Important ideas about matter such as volume, mass, and how matter changes state are conveyed through a series of easy-to-do experiments.