A highly engaging lesson that looks at the structures that are found in the mammalian heart and explores the functions of the heart as a pump as well as the function of the lungs such as gas exchange and respiration. This lesson has been designed for GCSE students but could be used as an initial recap with A-level students before they go on to learn this topic in greater detail The lesson begins by introducing the double circulatory system of mammals. A quick exercise is used to challenge the students to recognise the reason why mammals have a need for a double circulatory system. Time is taken to discuss the action of the cilia and goblet cells in the lungs. Moving forwards, students will learn that there are two types of circulation systems of the heart the details of their actions is explored. In addition to a game to maintain engagement, exam questions are added in towards the end to truly test the students knowledge and understanding of the topic.