This Web site from the Canadian Lung Association contains an excellent collection of learning resources about the respiratory system for grades 1-12. Content varies according to grade range; for instance, the section for grades 1-3 covers basics of lungs and their function with an illustrated story, coloring book, interactive games, and downloadable worksheets. Older students focus in on smoking, air pollution, and other issues in addition to covering respiratory system biology. As with the section for grades 1-3, resources for older students include loads of extras, such as word games and online quizzes. The site also offers a helpful teachers' guide.