Meaning, Methods and Reasons for Water Purification Basic Science Primary 3 Second Term Lesson Notes Week 6


Subject: Basic Science

Class: Primary 3

Term: Second Term

Week: 6

Topic: Meaning, Methods, and Reasons for Water Purification

Duration: 45 minutes

Entry Behaviour: Students are expected to have basic knowledge of water and its importance.

Key Words: Water, purification, clean, methods, reasons

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

  1. Define water purification.
  2. Identify at least three methods of water purification.
  3. Explain at least three reasons for water purification.

Embedded Core Skills: Critical thinking, observation, communication

Learning Materials:

  • Basic Science textbook for Primary 3
  • Pictures or diagrams of water purification methods
  • Samples of water purification materials like sand, charcoal, and chlorine

Reference Materials: Lagos State Scheme of Work, Basic Science Textbook 3


Meaning of Water Purification:

  1. Cleaning Water: Water purification means making water clean and safe to drink.
  2. Removing Impurities: It involves removing dirt, germs, and other harmful things from water.
  3. Water Purification: Water Purification means making dirty water clean for man and animal use

Methods of Water Purification:

  1. Boiling: Heating water until it bubbles removes germs and makes it safe to drink.
  2. Filtration: Passing water through a special filter removes dirt and particles.
  3. Chemical Treatment: Adding special chemicals like Alum or chlorine to water to kills germs and makes it safe.
  4. Distillation: Turning water into steam and then cooling it back into water removes impurities.
  5. UV Treatment: Exposing water to ultraviolet light kills germs and makes it clean to drink.

Reasons for Water Purification 

  1. Safety: Purifying water makes it safe to drink without getting sick.
  2. Health: Clean water prevents diseases caused by germs in dirty water.
  3. Cleanliness: Purified water tastes better and looks clear.
  4. Hygiene: Drinking purified water helps keep our bodies clean and healthy.
  5. Prevention: It prevents stomachaches and diarrhea caused by drinking dirty water.
  6. Protection: Purified water protects our bodies from harmful bacteria and viruses.
  7. Well-being: Drinking clean water helps us stay strong and energetic.
  8. Avoiding Illness: It helps avoid sicknesses like cholera and typhoid fever.
  9. Comfort: Purified water is refreshing and enjoyable to drink.
  10. Longevity: Having access to clean water improves our overall quality of life and longetivity.


  1. Water purification is the process of __________ water to make it safe for drinking. a) cleaning b) dirtying c) purifying d) coloring
  2. One method of water purification is __________  a) filtration b) soil c) sand d) rock
  3. Boiling water is a method of purification that kills __________. a) germs b) plants c) rocks d) clouds
  4. Adding chlorine to water helps __________ harmful bacteria. a) grow b) reduce c) multiply d) evaporate
  5. Filtration removes __________ from water. a) dirt particles b) clean c) salt d) sugar
  6. Water purification helps prevent __________ diseases. a) heart b) lung c) waterborne d) skin
  7. Purified water tastes __________. a) sweet b) sour c) bitter d) clean
  8. Boiling water for __________ minutes can make it safe to drink. a) 1 b) 5 c) 10 d) 20
  9. Water purification improves __________ health. a) mental b) physical c) emotional d) spiritual
  10. Dirty water can cause __________ and stomachaches. a) happiness b) sadness c) headaches d) dizziness
  11. Water purification helps us stay __________. a) weak b) strong c) tired d) lazy
  12. Adding __________ to water can remove impurities. a) salt b) sugar c) lemon d) bleach
  13. Water purification is important for __________ health. a) animal b) human c) plant d) insect
  14. Drinking purified water helps us __________. a) smile b) cry c) laugh d) stay healthy
  15. Purifying water helps __________ waterborne diseases. a) spread b) prevent c) increase d) ignore


  1. Revision: The teacher revises the previous topic on the sources and uses of water. Water: Meaning, Clean Qualities, Contaminants, Risks Basic Science Primary 3 Second Term Lesson Notes Week 5
  2. Introduction of New Topic: The teacher introduces the topic of water purification, explaining its meaning and importance.
  3. Teacher’s Activities:
    • Define water purification and its significance.
    • Explain different methods of water purification such as boiling, filtration, and chlorination.
    • Discuss the reasons why water purification is necessary, including removing harmful bacteria, viruses, and chemicals.
    • Show pictures or diagrams of water purification methods.
    • Conduct a demonstration of one or two water purification methods if possible.
  4. Learners’ Activities:
    • Listen attentively to the teacher’s explanation.
    • Participate in class discussions by asking questions and sharing ideas.
    • Observe the demonstration carefully.
    • Take notes on the key points discussed.
  5. Assessment: The teacher assesses students’ understanding through:
    • Asking questions during the lesson.
    • Observing students’ participation in class activities.
    • Reviewing students’ notes.
  6. Evaluation:
    1. What is water purification?
    2. Name three methods of water purification.
    3. Why is water purification important?
    4. What does boiling water help to remove?
    5. How does filtration purify water?
    6. What is added to water to kill harmful microorganisms?
    7. Give two reasons why we should purify water before drinking.
    8. Describe one method of water purification.
    9. What are the embedded core skills in learning about water purification?
    10. Can you explain the meaning of water purification to a friend?
  7. Conclusion: The teacher summarizes the key points of the lesson and addresses any remaining questions from students. The teacher then assigns homework related to water purification and encourages students to practice what they have learned.