She also understands why our garbage is separated out into recycling, compost, and actual garbage. I've explained that some items, like used paper, get broken down and turned into something new to save resources and space while others end up in a landfil, using up resources and space. Her Grampy, while gardening, explained the process of composting as she watched him take some compost and put it with new plants.
For expert ideas on how to raise eco-conscious kids, have a look at the book Eco-Kids by Dan Chiras. It has everything from small educational steps to methods for arranging an entire community to be eco-friendly.