Begin a unit on the body systems with a general lesson on the organization of systems. Explain to students that different systems have different functions. For instance, the digestive system primarily functions to help the body break down food in the stomach and use nutrients to fuel the body, while the respiratory system's primary function is to enable breathing and the distribution of oxygen and release of carbon dioxide. Review each of the body systems and their functions. In addition, provide examples of body systems working together. For instance, explain how the respiratory system and the circulatory system support each other to pump oxygenated blood to parts of the body.
Teach a lesson on the parts of the body systems to help students understand how different parts of the body work within different systems and how systems, which are an assembly of parts, are able to function in ways that single parts cannot. To reinforce this idea, explain how a bicycle wheel contributes to the overall function of a bicycle. Write the body systems on the blackboard. Create index cards with a picture of a body part and distribute the cards to students. Ask students to approach the board and place their card underneath the system to which it belongs. As a class, review the placement of cards and explain why certain classifications are correct. Note that some parts belong to more than one category, as they are used by more than one system of the body.
Include a lesson that teaches that certain parts of the body have multiple functions. Explain that some organs, muscles and parts perform different tasks that contribute to the workings of different systems. For instance, the male urethra produces sperm and release urine, making it a part of the reproductive system and the excretory system. Likewise, the pancreas produces hormones and digestive enzymes, making it part of the endocrine system and the digestive system. To reinforce this lesson, challenge students to identify body parts that belong to more than one system.
Present a lesson that teaches students how certain activities utilize different systems. Show students different objects and ask them to name the different systems that work with such objects. For instance, show students an apple and ask them to name the different systems of the body that work to eat, digest and excrete the apple. Show students a treadmill and ask them to identify the primary systems that enable the body to exercise. Emphasize that each of the systems of the body are necessary, as they help the body to function and perform everyday activities that are necessary to survival.