Composition: Expository Essay – JSS1 English Lesson Note (Third Term)

An expository essay explains a subject clearly using facts, reasons and examples. It does not tell a story or argue for one side. A good expository essay has an introduction, a body of organised points and a conclusion. The sample below explains the importance of trees.

Behavioural objectives

By the end of the lesson, students should be able to:

1. Explain what an expository essay is and name its three parts.
2. State the main benefits of trees given in the sample essay.
3. Explain how trees clean the air, help to cool the environment and save water.
4. Identify the economic benefits of trees.
5. Pick out the main points of an article as a basis for writing an essay.

What is an expository essay?

The word expository comes from expound, which means to explain in detail. An expository essay therefore explains how something works, why something happens, or what something is. Examples of topics are “The importance of reading” and “How rain is formed”.

What are the parts of an expository essay?

What features does an expository essay have?

• It sticks to facts and explanations.
• It is usually written in the simple present tense.
• It uses linking words such as also, moreover and because.
• Each paragraph deals with one point only.

Sample expository essay: the importance of trees

Introduction

Trees are important plants that give us many of the things we need to live. This essay explains how trees support life, cool the environment, clean the air, save water, protect the soil, bring economic benefits and improve health and mood.

How do trees support life?

During photosynthesis, trees use carbon dioxide, water and sunlight to make carbohydrates (food). This food supports the growth of the fruits and leaves eaten by humans, such as mangoes and oranges, and by animals, such as elephants and giraffes.

Trees also provide wood and charcoal, which are used as fuel, and timber, which is used to build houses. Moreover, trees provide a home for bees, birds and squirrels.

How do trees help to cool the environment and fight climate change?

Trees absorb carbon dioxide, a gas that traps heat in the atmosphere, and release oxygen. This helps to keep the air fresh and reduces the build-up of gases that cause climate change.

Trees also moderate the effects of the sun, rain and wind. They give shade to homes and streets. They also release water vapour into the air. Both of these help to lower the temperature.

How do trees clean the air?

Trees remove dust and filter particles from the air, trapping them in their leaves and bark. They also absorb some harmful gases, such as nitrogen oxides.

How do trees save water?

When it rains, trees soak up water and store it in the soil around them. This reduces runoff, so more water stays in the ground. Tree shade also slows the evaporation of water into the atmosphere.

How do trees protect the soil?

Tree roots hold the soil in place and help to prevent soil erosion during heavy rain and floods. Leaves and branches also break the fall of raindrops, so the rain hits the ground with less force.

What economic benefits do trees bring?

Planting trees creates jobs in fruit harvesting, timber work, building, furniture making and the production of paper and books.

Trees planted close to houses give shade, so people need fewer fans or air conditioners to keep cool. This lowers the cost of electricity. Houses surrounded by well-kept trees and gardens are also usually worth more.

How do trees improve health and mood?

Trees help people to relax and heal. Because of their many shapes, sizes and colours, they lift people’s moods.

Conclusion

Trees give us food, clean air, water, shade and work. They are valuable to people, animals and the environment.

Evaluation

1. What is an expository essay?
2. Name the three parts of an expository essay.
3. Which part of the essay is made up of several paragraphs, each with one main point?
4. Name the process in which trees use carbon dioxide, water and sunlight to make food.
5. Study the sample essay and list its main points as the basis for your own essay.

Answer key for teachers

1. An essay that explains a subject clearly using facts, reasons and examples.
2. Introduction, body and conclusion.
3. The body.
4. Photosynthesis.
5. Main points: trees support life; trees cool the environment and fight climate change; trees clean the air; trees save water; trees protect the soil; trees bring economic benefits; trees improve health and mood.

Assignment

From the list of main points, choose any three. Write a short expository essay of five paragraphs on the importance of trees: an introduction, three body paragraphs (one for each point you chose) and a conclusion.