4Sustainability means trying to avoid using up natural resources so as to keep Earth's ecosystems in balance. Some sustainability practices include composting, limiting use of cars and other vehicles that use fossil fuels, and investing in solar power for your home. This title introduces to the main concept of sustainability in an age-appropriate way, including environmental and Earth science topics in the main content. Case studies gives readers relatable examples and tips on how to live more sustainably now and in the future--and how that will impact Earth.