In this lesson, students explore how the human body protects itself against pathogens. The session begins with a recap discussion to activate prior knowledge about pathogens and infection. Students are then guided through the body’s main defence mechanisms, focusing on how the immune system recognises self and non-self cells.
Using teacher-led explanations, questioning, and visual examples, students examine physical and chemical barriers such as skin, mucus, and stomach acid, before comparing non-specific (innate) and specific (adaptive) immunity. The lesson concludes with a clear explanation of the inflammatory response, linking structure to function and reinforcing key terminology.
Throughout the lesson, students check understanding through verbal questioning, think–pair–share activities, and short on-screen retrieval tasks. No printing is required; all resources are displayed digitally.

Learning Objectives (LOs)
By the end of the lesson, students will be able to:
Define the main defence mechanisms of the body
Explain how the body distinguishes between its own cells (self) and foreign cells (non-self)
Describe physical and chemical barriers to infection
Explain the difference between non-specific and specific immunity
Describe the inflammatory response