Robert Gardner 
How Heavy is Heavy? [PDF ebook] 
Science Projects with Weight

Have you ever been weightless? Does your weight change when you sit or lie down? How do you weight air? There are many things, light and heavy in the world around you which you can measure. The concepts introduced in this book will help you perform exciting and fun experiments. Some will even give you ideas for your science fair. All you need are some simple materials, most of which can be found around your home, school, or neighborhood. You will then be ready to discover the world of weight!