Ward, D. J

"Millions of people live in cities around the world, but have you ever wondered how cities work? All those people need clean water to drink, a safe place to live, and a way to get all around the city! How do you take care of all those people's needs? Your city has a plan for that. Read and find out all about the systems a city has to help keep everyone safe, healthy, and happy"--Provided by publisher.

Describes the six simple machines: the lever, the wheel and axle, the pulley, the ramp, the wedge, and the screw.

Explains how scientists study materials at the microscopic level and then use that knowledge to create supermaterials.

Explains how people create too much waste, how it is disposed of in landfills, and how we need to increase recycling.