Science at key stage 3 (Year 8)
Unit 8A: Food and digestion
Section 8: a. What happens to food inside the digestive system?
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Objectives |
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- that the digestive system consists of a tube through which food passes
- to interpret the relationship between a model gut and the digestive system
- to suggest explanations for observations
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Activities |
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Outcomes |
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Children: |
- Ask pupils for their ideas about what happens to food once it has been eaten. Develop the idea that food enters a tube running through the body, and that this, and associated organs, make up the digestive system. Build up their suggestions into a sequence of events commencing with feeding, followed by absorption and ending with elimination of faeces.
- Explain that what happens to food inside this tube can be explored using a model,
eg a model gut made from visking tubing filled with a 'starch meal'; a software simulation. Ask pupils about how they tested for starch earlier and help them to test the contents of the 'gut' and the surrounding water for starch. Ask pupils to explain their observations and to consider the implications of nutrients from food entering the body.
- Ask pupils to interpret their findings in the light of their previous assumptions.
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- describe how food passes along a digestive tube which runs through the body
- offer suggestions about what happens to food as it passes through this tube
- make links between the model gut and the digestive system
- use scientific knowledge to explain observations
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Points to note |
- Most pupils will not have studied digestion at key stage 2, although they will have ideas about what happens to food inside the body. This unit focuses on what digestion involves and why it is necessary, rather than on the structure of the digestive system or on the detail of how and where particular foods are digested.
- The use of the model gut will allow pupils to investigate the processes going on inside the intestine, and to appreciate the importance of the process. Using a model such as a sieve with chickpeas and sand may help some pupils.
- Pupils are introduced to the particle model in unit 7G 'Particle model of solids, liquids and gases' and to ideas about atoms and molecules in unit 8E 'Atoms and elements'.
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This unit is divided into sections. Each section contains a sequence of
activities with related objectives and outcomes. You can view this unit by
moving through the sections or print/download the whole unit.
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