Organisms: The Human Digestive System – Year 9
How Does the Body Turn Food into Energy? (PPT + Worksheet)

This lesson explores the structure and function of the human digestive system, guiding students through the journey food takes from mouth to absorption. Pupils identify the organs of the alimentary canal and their functions, explain the difference between mechanical and chemical digestion, sequence how food moves through the digestive tract, and describe the role of auxiliary organs such as the liver and pancreas. The lesson combines clear diagrams, sequencing tasks and analytical discussion to build understanding of how digestion supports life.

• Identify the organs of the alimentary canal and their functions — mouth, oesophagus, stomach, intestines and rectum.
• Explain the difference between mechanical and chemical digestion — physical breakdown vs enzyme‑driven reactions.
• Sequence how food moves through the digestive tract — tracing the journey from ingestion to egestion.
• Describe the role of auxiliary organs like the liver and pancreas — bile production, enzyme secretion and nutrient processing.

• KS3 Biology: Organ systems, digestion and nutrition
• Working Scientifically: Modelling, sequencing and explaining biological processes

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