The chapter why do we fall ill is aimed to teach students about healthy habits and how they can stay healthy. The topics covered in this chapter are health and it’s failure, what are community health issue and personal health issues. In this chapter, one important topic from the examination point of view is the difference between healthy and disease free. To make students aware of different diseases and it’s symptoms there is a module which is disease and its cause. The revision notes for class 9 chapter 13 why do we fall ill is given here so that students don’t have to make their own notes and can study without wasting a single minute.