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BIOLOGY LESSON NOTE ON HUMAN KIDNEY

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Lesson Note on the Human Kidney Topic: The Human Kidney Duration: 40 minutes Specific Objectives: By the end of the lesson, students should be able to: Define the kidney and state its location in the human body. Identify and describe the structure and functions of the kidney. Explain the processes involved in urine formation (filtration, reabsorption, and secretion). Describe how the kidney contributes to homeostasis. Identify common kidney-related diseases and how to prevent them. Evaluate the importance of maintaining kidney health. Lesson Content: 1. Introduction to the Human Kidney The kidneys are vital organs in the human body responsible for filtering waste from the blood and regulating water and electrolyte balance. They are part of the excretory system and play a crucial role in homeostasis. Location: The kidneys are located in the abdominal cavity, on either side of the spine, just below the rib cage. Each kidney is bean-shaped and about the size of a fi...
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BASIC SCIENCE LESSON NOTE ON CHANGES IN MATTER (PHYSICAL AND CHEMICAL CHANGES) (JSS1 SECOND TERM LESSON NOTE)

Class

JSS1

Term

Second Term

Week

Week 4

Topic

Changes in Matter (Physical and Chemical Changes)

Duration

40 Minutes

Instructional Materials

  • Ice block
  • Water
  • Candle and matches
  • Piece of paper
  • Iron nail
  • Vinegar
  • Baking soda
  • Sugar
  • Charcoal
  • Chalk
  • Chart showing physical and chemical changes

Reference Books

  1. NERDC Basic Science Curriculum for JSS.
  2. STAN Basic Science for Junior Secondary Schools.
  3. Evans Basic Science for Junior Secondary Schools.
  4. Comprehensive Basic Science by A.O. Ogunniyi.

Specific Objectives

At the end of this lesson, students should be able to:

  1. Define change in matter.
  2. Explain physical change.
  3. Explain chemical change.
  4. Differentiate between physical and chemical changes.
  5. Give examples of physical and chemical changes in everyday life.
  6. State the characteristics of physical and chemical changes.

Introduction

Matter can exist as solids, liquids or gases. Under certain conditions such as heating, cooling or mixing with other substances, matter can change from one form to another.

For example:

  • Ice melts to form water.
  • Water evaporates to become water vapour.
  • Iron rusts when exposed to air and moisture.
  • Wood burns to form ash and smoke.

Some changes are temporary and reversible, while others are permanent and irreversible.

These changes are grouped into:

  1. Physical changes
  2. Chemical changes

Meaning of Change in Matter

A change in matter is any process that alters the form, shape, size or composition of a substance.

Matter may undergo changes due to:

  • Heating
  • Cooling
  • Burning
  • Mixing substances
  • Exposure to air
  • Pressure

Types of Changes in Matter

There are two major types:

  1. Physical Change
  2. Chemical Change

Physical Change

A physical change is a change in which no new substance is formed.

The substance only changes in:

  • Shape
  • Size
  • State
  • Appearance

The original substance can usually be recovered.

Characteristics of Physical Changes

  1. No new substance is formed.
  2. The chemical composition remains unchanged.
  3. The change is usually temporary.
  4. The process is reversible.
  5. Only the physical properties change.
  6. Energy change is usually small.

Examples of Physical Changes

1. Melting of Ice

Ice changes into water when heated.

Ice → Water

No new substance is formed because both ice and water are made of water molecules.

2. Freezing of Water

Water changes into ice when cooled.

Water → Ice

This process is reversible.

3. Evaporation

Water changes into water vapour when heated.

Water → Water vapour

No new substance is formed.

4. Condensation

Water vapour changes into liquid water when cooled.

Water vapour → Water

5. Dissolving Sugar in Water

Sugar dissolves in water but can be recovered by evaporation.

6. Cutting Wood

When wood is cut into smaller pieces, its size changes but it remains wood.

7. Breaking Glass

Breaking a bottle changes its shape but no new substance is produced.

Chemical Change

A chemical change is a change in which one or more new substances are formed.

The original substance changes completely into another substance with different properties.

Chemical changes are usually permanent and cannot easily be reversed.

Characteristics of Chemical Changes

  1. New substances are formed.
  2. The change is permanent.
  3. The process is difficult or impossible to reverse.
  4. Energy is absorbed or released.
  5. Colour change may occur.
  6. Gas may be produced.
  7. A precipitate may be formed.
  8. Heat or light may be produced.

Examples of Chemical Changes

1. Burning of Paper

When paper burns:

  • Ash is formed.
  • Smoke is produced.
  • Heat and light are released.

The paper cannot be recovered.

2. Rusting of Iron

Iron reacts with oxygen and moisture to form rust.

Iron + Oxygen + Water → Rust

Rust is a new substance with different properties.

3. Cooking of Food

During cooking:

  • New substances are formed.
  • The taste, colour and texture change permanently.

4. Burning of Wood

Wood burns to produce:

  • Ash
  • Smoke
  • Carbon dioxide
  • Heat

The process is irreversible.

5. Souring of Milk

Fresh milk changes into sour milk due to bacterial action.

The change is permanent.

6. Digestion of Food

Food eaten by humans undergoes chemical changes in the digestive system.

Nutrients are broken down into simpler substances.

Differences Between Physical and Chemical Changes

Physical Change Chemical Change
No new substance is formed New substance is formed
Usually reversible Usually irreversible
Temporary Permanent
Only physical properties change Chemical composition changes
Small energy change Large energy change
Examples: melting, freezing Examples: burning, rusting

Physical Changes in Daily Life

Examples include:

  1. Melting butter.
  2. Drying clothes under the sun.
  3. Crushing pepper.
  4. Cutting paper.
  5. Dissolving salt in water.
  6. Breaking bottles.
  7. Freezing water to make ice.

Chemical Changes in Daily Life

Examples include:

  1. Cooking yam.
  2. Burning charcoal.
  3. Baking bread.
  4. Rusting of iron roofing sheets.
  5. Digestion of food.
  6. Ripening of fruits.
  7. Fermentation of palm wine.

Importance of Studying Changes in Matter

The study of changes in matter helps us to:

  1. Understand industrial processes.
  2. Improve food processing.
  3. Prevent rusting of metals.
  4. Manufacture medicines.
  5. Produce chemicals used in homes and industries.
  6. Understand environmental changes.
  7. Improve agricultural practices.

Practical Activities

Activity 1

Take an ice block and leave it in the open.

Observation:

The ice melts to form water.

Conclusion:

Melting is a physical change.

Activity 2

Burn a piece of paper.

Observation:

Ash and smoke are produced.

Conclusion:

Burning is a chemical change.

Activity 3

Dissolve sugar in water.

Observation:

Sugar disappears but can be recovered.

Conclusion:

Dissolving sugar is a physical change.

Activity 4

Expose an iron nail to moisture for several days.

Observation:

Rust forms on the nail.

Conclusion:

Rusting is a chemical change.

Signs That a Chemical Change Has Occurred

The following signs indicate a chemical change:

  1. Formation of a new substance.
  2. Production of gas.
  3. Colour change.
  4. Formation of a precipitate.
  5. Release of heat.
  6. Emission of light.
  7. Permanent change in properties.

Advantages of Chemical Changes

  1. Production of useful materials.
  2. Cooking of food.
  3. Manufacture of medicines.
  4. Production of cement.
  5. Generation of energy.

Harmful Effects of Chemical Changes

  1. Rusting destroys metals.
  2. Food spoilage causes waste.
  3. Corrosion damages machines.
  4. Burning fuels pollutes the environment.
  5. Chemical reactions can produce harmful substances.

Conclusion

Matter undergoes different kinds of changes. These changes are classified as physical and chemical changes. Physical changes do not produce new substances and are usually reversible, while chemical changes produce new substances and are mostly irreversible. Understanding these changes helps us explain many natural and industrial processes around us.

Evaluation

Answer the following questions:

  1. What is change in matter?
  2. Define physical change.
  3. Define chemical change.
  4. State five characteristics of physical changes.
  5. State five characteristics of chemical changes.
  6. Mention five examples of physical changes.
  7. Mention five examples of chemical changes.
  8. Differentiate between physical and chemical changes.
  9. Explain rusting of iron.
  10. State four signs of chemical change.

Objective Questions

Choose the correct answer from A – D.

  1. A physical change is a change in which ______.

A. new substances are formed
B. no new substance is formed
C. heat is always released
D. gases are produced

Answer: B

  1. Which of the following is a physical change?

A. Rusting of iron
B. Burning wood
C. Melting ice
D. Cooking food

Answer: C

  1. Which of these is a chemical change?

A. Breaking glass
B. Dissolving sugar in water
C. Cutting wood
D. Burning paper

Answer: D

  1. Rusting of iron is an example of ______.

A. Physical change
B. Chemical change
C. Temporary change
D. Reversible change

Answer: B

  1. Which of the following is reversible?

A. Burning charcoal
B. Rusting iron
C. Melting ice
D. Cooking yam

Answer: C

  1. Which of these indicates a chemical change?

A. Formation of a new substance
B. Change in shape only
C. Breaking into pieces
D. Change in size

Answer: A

  1. The burning of wood produces ______.

A. Water only
B. Smoke and ash
C. Oxygen
D. Ice

Answer: B

  1. Which of the following is NOT a physical change?

A. Freezing water
B. Evaporation
C. Condensation
D. Digestion of food

Answer: D

  1. Dissolving salt in water is a ______.

A. Chemical change
B. Permanent change
C. Physical change
D. Irreversible change

Answer: C

  1. Which process forms a new substance?

A. Cutting paper
B. Melting wax
C. Burning paper
D. Breaking glass

Answer: C

Essay Questions

  1. Define physical change and discuss its characteristics with examples.

  2. Explain chemical change and state its characteristics.

  3. Differentiate between physical and chemical changes using a table.

  4. Discuss five examples of physical changes and five examples of chemical changes in everyday life.

  5. Explain the signs that indicate a chemical change has occurred.

Assignment

  1. State ten examples of physical changes occurring around you.

  2. State ten examples of chemical changes occurring in your environment.

  3. Draw a table showing at least six differences between physical and chemical changes.

  4. Explain why: a. Melting ice is a physical change.
    b. Burning paper is a chemical change.
    c. Rusting of iron is irreversible.

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