A blue exercise book is a type of notebook that is typically used for writing and taking notes. It is usually small and portable, and it has a cover that is made of blue paper or blue cardstock. The pages of a blue exercise book are typically lined or unlined, and they may have a hole punch along one edge so that the book can be easily stored in a binder. Blue exercise books are often used by students in schools or universities to take notes during lectures or to complete homework assignments. They are also commonly used by professionals for taking notes during meetings or for jotting down ideas and thoughts.