Class Four Science: Chapter One, Health Principles

All Class Four Science Chapters

AKey Terms and Concepts

Good health is important for our well-being. In this chapter you will learn how to keep your body strong and safe: eating a balanced diet, exercising, keeping clean, and reading safety signs and product information.

1Concept of Health Principles

• Following health principles is important for staying healthy. Good health means being strong in both body and mind.
• To be healthy, you need to eat a balanced diet, do physical exercises regularly and keep your body and environment clean.
• It is also important to follow safety signs and health information in the environment.

2Balanced Diet

• A balanced diet is a meal with all the food nutrients in the correct proportions. It is made up of foods from three main groups.
• The groups are energy-giving foods, body-building foods and protective foods.
• Energy-giving foods have carbohydrates and fats. Body-building foods have proteins. Protective foods have vitamins and minerals.
• A balanced diet helps make the body's immune system strong to fight diseases.

Energy-giving foods

• Foods rich in carbohydrates and fats give the body energy.
• Carbohydrate-rich foods: maize, potatoes, cassava, bananas, rice and bread.
• Foods rich in fats: coconut, peanuts, sunflower seeds and avocados.
• They provide energy for daily activities like playing, farming and walking. Fats also help keep the body warm.

Body-building foods

• Body-building foods are rich in protein: fish, milk, meat, eggs, beans and peas.
• They help build the body and promote proper growth.
• They also help make new cells to replace old or dead ones.

Protective foods

• Protective foods are rich in vitamins and minerals. They support overall body health and help the body defend itself against diseases.
• They also help build and strengthen muscles and bones.
• Vegetables: cabbage, spinach, eggplant, amaranth (mchicha) and carrot.
• Fruits: papaya, orange, avocado, grape and mango.

Water

• The body needs enough water to work properly, but water is not a main food group in a balanced diet.
• Water contains minerals that help body systems work properly.
• It helps break down food in the digestive system.
• It regulates body temperature and helps nutrient absorption.
• It helps remove waste and harmful substances from the body.

3Balanced Diet for Different Groups of People

• Nutritional needs differ between groups of people. Groups are based on age (children, adolescents, the elderly), the work people do (manual workers) and health status (the sick).

Children

• Children need foods rich in protein because they are growing: milk, meat, fish, beans, peas, lentils and eggs.
• These foods build the body, strengthen the immune system and support brain development.
• Children also need energy-giving foods for playing, and protective foods to make their immune system strong.

Adolescents

• During adolescence the body grows fast and changes. Adolescents need body-building, protective and energy-giving foods.
• They are busy with sports, farming and long hours of study, so their diet should include plenty of energy-giving foods.

Elderly

• The elderly need foods rich in vitamins to protect them from illness, because the immune system gets weaker with age.
• They need minerals to keep bones and muscles strong.
• A small amount of energy-giving foods is enough for light activities and helps avoid gaining too much weight.
• Body-building foods replace old or damaged cells.

Manual workers

• Manual workers include porters, cart pushers, mechanics and construction workers.
• They need a large amount of energy-giving foods for heavy tasks.
• They should drink plenty of water to aid digestion and replace water lost through sweat.

Sick people

• A balanced diet helps a sick person's body fight disease and regain strength.
• They should eat more foods that build and protect the body, to repair cells and tissues damaged by illness.
• These foods also make the muscles, bones and immune system strong.
• Food needs differ with the type of illness, so sick people should eat as advised by health professionals.

4Physical Exercises

Physical exercises keep the body healthy. They include playing football, running, jumping and walking.

Benefits of exercising

Regular physical exercise helps to:

• stay healthy and strong;
• keep body systems, like digestion and excretion, working well;
• strengthen body immunity to fight diseases;
• reduce stress; and
• refresh the mind and have fun.

Effects of not exercising

Lack of exercise can cause:

• poor health and a weak body;
• gaining too much weight, leading to obesity;
• chronic diseases such as high blood pressure, diabetes and heart problems;
• stress; and
• weak muscles and bones.

5Personal and Environmental Hygiene

Keeping the body and the environment clean is important for good health.

Personal hygiene

Personal hygiene includes cleaning the mouth, skin, hair, nails and clothes, using proper tools.

Oral hygiene

• Clean the mouth with a toothbrush, toothpaste and clean, safe water. Brushing removes food particles from the teeth.
• If food particles remain, bacteria feed on them and produce acid. The acid damages teeth and causes cavities.
• Brush at least twice a day: in the morning and at night before bed.

Bathing

• Use clean water and soap. Bathe every day, in the morning and evening, to avoid skin diseases.
• If we do not bathe, our bodies smell bad. After bathing, dry with a clean towel.
• Body oil keeps the skin soft and stops it drying.
• Wash your face with clean water and soap after waking up to remove rheum and prevent eye diseases.

Hair hygiene

• Wash hair regularly with clean water and soap. Braid, shave or comb it to look neat.
• Clean hair helps prevent dandruff, lice and scalp infections such as ringworm.

Nail hygiene

• Keep fingernails and toenails short and clean. Long nails can hold dirt with germs that cause diseases.
• Washing hands and nails with clean running water and soap removes and kills these germs.

Clothing hygiene

• Wash clothes with clean water and soap. Dirty clothes can cause body odour and skin problems like itching and rashes.
• Dry clothes properly and iron them. Ironing helps kill germs and keeps clothes neat.

Environmental hygiene

• Dirty places attract houseflies and mosquitoes, which spread diseases like diarrhoea, cholera and malaria.
• Breathing polluted air can cause respiratory diseases, which make our bodies weak.
• To stay healthy and strong, we must keep our surroundings clean.

6Safety Signs in the Environment

Signs and symbols guide us in our environment. They can be words or pictures and give instructions to keep everyone safe.

Types of safety signs

There are four main types: warning, prohibition, mandatory and emergency signs. Each has its own colour and shape, following international safety rules.

Warning signs

• They alert us to dangers that might happen, on roads, in the school compound or on things like waste bins.
• They have a yellow background and are triangular, with a black picture and black borders.

Prohibition signs

• Also called regulatory signs. They show things that are not allowed.
• They have a black picture on a white background with a red circular border, and often a red diagonal line.
• Examples: “No Entry” and “No Eating or Drinking”.

Emergency signs

• They tell us what to do in emergencies like accidents, and show safe places, directions to safety or helpful equipment such as emergency phones and first aid kits.
• They are rectangular, with white pictures on a green background (or green pictures on white).

Mandatory signs

• They tell you what you must do in an area, such as a chemical storage area.
• They are blue and circular, with a white picture in the middle.

7Important Information for Protecting Our Health

We should pay attention to important details on products we use every day. The key details are the expiration date, instructions for use, ingredients and storage methods.

Expiration date

• The expiration date is the last day a product is safe to use.
• Do not use products after this date, because they may harm your health.
• It may be written as “Expiry date” or in short forms such as “ED”, “EXP” or “E”.

Instructions for use

• Read and understand the instructions before using any product, so you use it correctly and stay healthy.
• For example, medicine must be taken in the right amount to reduce risks to people and the environment.

Ingredients

Products contain various ingredients. Knowing what is in a product helps prevent health problems such as allergies.

Storage methods

• Storing products correctly keeps them safe to use. Follow the storage instructions.
• This information is usually written on the packaging.

8Chapter Summary

9End of Topic Questions