Identify the primary function of the major human organ systems and describe how two or more systems cooperate during one activity.
Your body runs on roughly a dozen organ systems, each with its own main job, none of them working in isolation. The skeletal system supports the body and protects organs; the muscular system moves it. The nervous system senses the world and sends fast electrical signals; the endocrine system sends slower chemical signals (hormones) for things like growth and mood. The digestive system breaks food into usable nutrients; the circulatory system carries those nutrients, plus oxygen, everywhere they are needed. The respiratory system brings in oxygen and removes carbon dioxide; the excretory system filters waste from the blood; the immune system defends against pathogens.
No system finishes its job alone. Eating an apple only matters because digestion breaks it down, circulation carries the nutrients, respiration supplies the oxygen needed to use them, and the nervous system coordinates the whole process without you consciously thinking about it. Learning body systems means learning both what each one does by itself, and how it depends on the others.
Mastery looks like: They can state the main job of each major system and trace at least one real activity through three or more cooperating systems.
Common stumbles: Learning each system as an island with no connections; confusing the fast, wire-like nervous system with the slower, chemical endocrine system.