Digestion and Teeth — Year 4 Lesson Plan
National Curriculum: Science Year 4 — Animals including humans: digestive system, teeth, food chains
Overview
Pupils learn about the human digestive system, tracing the journey of food from mouth to large intestine. They explore the role of teeth in mechanical digestion, the function of each organ in the digestive system, and the importance of food chains in understanding how animals get the energy they need.
Digestion and Teeth learning objectives
- Describe the function of each organ in the human digestive system.
- Identify different types of human teeth and explain their functions.
- Construct and interpret food chains showing producers, consumers, and predators.
- Explain what happens to food at each stage of digestion.
Success criteria
- I can name the main parts of the digestive system in order.
- I can describe what happens to food in each part.
- I can name incisors, canines and molars and say what each does.
- I can build a food chain with a producer and consumers.
Key Vocabulary
Suggested Lesson Structure
Ask: what happens to a sandwich after you eat it? Collect pupils' ideas and place them on a 'journey of food' timeline. Introduce the digestive system as a long tube — approximately 9 metres if stretched out — that processes everything you eat.
Trace the journey of food: mouth (chewing — mechanical digestion; saliva — chemical digestion begins) → oesophagus (peristalsis — muscular contractions push food down) → stomach (acid breaks down proteins; food mixed into a paste called chyme) → small intestine (most nutrients absorbed through villi into the bloodstream; bile from the liver emulsifies fats) → large intestine (water absorbed; waste compacted) → rectum/anus (waste expelled). Teeth: incisors (cutting), canines (tearing), premolars and molars (grinding). Milk teeth and adult teeth. Tooth decay — acids from bacteria attack enamel. Food chains: producer (plant) → primary consumer (herbivore) → secondary consumer (carnivore/omnivore). Show energy flow: most energy is lost at each level.
Pupils label a diagram of the digestive system using a word bank, then annotate each organ with its function. Then complete three food chains from a given set of organisms, identifying the producer and each level of consumer.
Pupils create a 'digestive system story' — written from the perspective of a piece of food travelling through the body, describing what happens at each stage using scientific vocabulary. Must mention at least five organs and two chemical processes.
Discuss: why do we need such a long digestive system? (more surface area for absorption). Why do carnivores have longer canines but shorter digestive systems than herbivores? Connect food chains back to energy: why can the Earth support more herbivores than carnivores?
Support and extension for digestion and teeth
Support
- Give a body outline with the organs as cut-outs to place and label.
- Use a mirror so pupils can find their own incisors, canines and molars.
- Provide the food chain arrows already drawn for pupils to add organisms.
Extension
- Explain why the small intestine is long and folded.
- Compare the teeth of a herbivore, a carnivore and an omnivore and link them to diet.
- Make a longer food chain or a simple food web and explain what happens if one animal is removed.
Check for understanding
Quick questions for the plenary or an exit ticket. Tap a question to see the answer.
1. Put in order: stomach, mouth, small intestine, oesophagus.
Answer: Mouth, oesophagus, stomach, small intestine.
2. What do molars do?
Answer: They grind and chew food.
3. Where are most nutrients absorbed into the blood?
Answer: The small intestine.
4. In the food chain grass → rabbit → fox, which is the producer?
Answer: The grass.
Resources you will need
- Digestive system diagram and body outline
- Hand mirrors
- Model teeth or images of animal skulls
- Food chain picture cards
Common Misconceptions
- Food falls straight to the stomach — peristalsis actively moves food; you could eat upside down and food would still reach the stomach.
- The large intestine absorbs most nutrients — it mainly absorbs water; most nutrient absorption happens in the small intestine.
Prior Knowledge
Pupils should already be able to:
- Year 3: nutrition and the need for a balanced diet.
- KS1: basic understanding that animals need food for energy.
- Basic understanding of what a food chain shows.
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