Science · Year 4

Active learning ideas

The Human Digestive System

Take your pupils on an incredible journey inside the human body! This topic uncovers the fascinating process of how a simple sandwich is transformed into the fuel we need to live and play.

• National Curriculum Attainment Targets
• National Curriculum for England: Science Year 4: Animals, including humans

• 15–45 min
• Pairs → Whole Class
• 3 activities

Activity 01

• Simulation Game
• 20 min · Pairs

Digestion in a Bag

Pupils model the stomach using a sealable plastic bag. They add a cracker (food), some water (saliva), and a small amount of orange juice (stomach acid), then mash the bag with their hands to simulate mechanical digestion.

Explain the journey of a piece of food from the mouth to the large intestine.

Facilitation Tip

Ensure you relate each physical component and action back to the corresponding part of the human digestive system.

What to look for

Pupils complete an 'exit ticket' where they label a blank diagram of the digestive system or write one sentence describing the function of the stomach.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

Activity 02

• Simulation Game
• 45 min · Small Groups

The Human Body Map

In small groups, one pupil lies on a large sheet of paper while others draw their outline. The group then draws and labels the main organs of the digestive system in the correct positions inside the outline.

Identify the main organs involved in digestion and describe their roles.

Facilitation Tip

Provide pre-printed images of organs that pupils can colour, cut out, and stick on to help with accuracy.

What to look for

Create a comic strip or a short presentation that tells the story of a piece of food travelling through the digestive system, explaining what happens at each stage.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

Activity 03

• Simulation Game
• 15 min · Whole Class

Stringing It All Together

Pupils use a long piece of string (around 7 metres) to represent the length of the small intestine. This provides a powerful visual and kinaesthetic way to understand the scale of the digestive tract inside their bodies.

Compare the function of the stomach with the function of the small intestine.

Facilitation Tip

Have pupils work together to stretch the string across the classroom to appreciate its full length.

What to look for

Pupils use a traffic light system (red, amber, green) to indicate their confidence in naming the digestive organs and describing their functions.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

A few notes on teaching this unit

Use a variety of visual aids, such as diagrams, videos, and physical models to make this internal process tangible. Begin with a simple, linear overview of the food's journey before delving into the specific function of each organ. Hands-on activities like the 'Digestion in a Bag' model are highly effective for consolidating understanding of the stomach's role.

By the end of this topic, pupils will be able to trace the path of food through the body, naming the key organs involved and explaining the important job that each one does.

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Watch Out for These Misconceptions

• The stomach does all the work of digestion.

  Digestion is a long process that starts in the mouth with chewing and saliva. The stomach breaks food down further, but the small intestine is where most of the nutrients are absorbed into the body.

• Food just falls down a tube into your stomach.

  The oesophagus is a muscular tube. It pushes food down into the stomach using waves of muscle contractions, a process called peristalsis. This means you can even swallow if you are upside down.

• Stomach acid is the only thing that breaks down food.

  The stomach uses both acid and special chemicals called enzymes to break down food. The churning, muscular action of the stomach wall also helps to physically mash the food into a paste.

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Methods used in this brief

• Simulation Game