Science & Technology — Living Things

Subtopic: Human Body — The Digestive System

Age: 9 years (Kenyan primary level) • Use simple examples: ugali, rice, chapati, fruits

Learning goals (what you will learn)

• What the digestive system is and why we need it.
• Main parts of the digestive system and what each part does.
• How to keep the digestive system healthy.

What is digestion?

Digestion is the process by which the body breaks down food into smaller parts so the body can use the nutrients for energy, growth and repair. Food is changed from big pieces into tiny bits that blood can carry to every part of the body.

Two main parts of digestion

• Mechanical digestion: chewing with teeth and stomach churning (mixing).
• Chemical digestion: juices (like saliva and stomach acid) break food into tiny chemicals (nutrients).

Main parts and their jobs

• Mouth — teeth chew food; saliva (spit) starts to break it down. Example: chew ugali well!
• Oesophagus (food pipe) — a tube that pushes the food down to the stomach.
• Stomach — mixes food with stomach juices; starts breaking proteins.
• Small intestine — most digestion happens here; nutrients move into the blood.
• Large intestine (colon) — takes water back into the body and forms faeces (poo).
• Liver — makes bile which helps to break down fats (oils).
• Gall bladder — stores bile and releases it into the small intestine.
• Pancreas — makes juices that help digest food in the small intestine.

Simple visual: a child-friendly digestive path

Class activity (safe and simple)

1. Draw and label the digestive system on paper using the diagram above.
2. Make a model "stomach" in a zip-lock bag: put a small piece of banana, add warm water and mash with your hands (with teacher help). This shows mechanical and liquid mixing in the stomach. Wash hands before and after.

How to look after your digestive system

• Eat a balanced diet: vegetables, fruits (mango, oranges), ugali, beans, milk.
• Eat fibre-rich foods (greens, fruits) to avoid constipation.
• Drink plenty of clean water every day.
• Chew food slowly and well before swallowing.
• Wash hands with soap before eating to avoid germs and worms.
• Visit the school health nurse if you have stomach pains or feel unwell.

Common problems to watch for

• Stomach ache — tell an adult.
• Constipation — eat more fruits and drink water.
• Worms — keep clean, and get medicine from the clinic if told by a nurse.

Words to remember (Glossary)

• Digestion — changing food into small parts the body can use.
• Saliva — watery liquid in the mouth that starts chemical digestion.
• Stomach — organ that mixes and breaks down food.
• Intestine — tube where food is digested and nutrients are absorbed.
• Bile — liquid from the liver to digest fats.

Quick quiz (try these)

1. Where does digestion start?
2. Name two jobs of the stomach.
3. Which organ absorbs most nutrients?
4. Give one way to keep the digestive system healthy.
5. What does the large intestine do?

Teacher note: Use local food examples (ugali, matoke, chapati) and simple classroom activities. Always supervise hands-on activities and keep them clean and safe.