General Science Grade 8 Textbook Notes

Title Page

  • Addis Ababa City Administration Education Bureau
  • General Science
  • Student Textbook ETRSS-1 Grade 8

Authors & Contributors

  • Authors: Yonas Nibret (BSc., MA), Sefiw Melesse (MSc.), Abebe Habte (MSc)
  • Editors: Getahun Getachew (BEd), Muluneh T/Birhan (BEd), Ali Kemal (MEd)
  • Coordinator: Getachew Talema (MA)
  • Layout Design & Art: Entoto Polytechnic College (T.M.S)

Care for Textbook

  1. Cover the book with protective materials (plastic, old newspapers, or magazine).
  2. Keep the book in a clean dry place.
  3. Ensure hands are clean when using the book.
  4. Do not write on the cover or inside pages.
  5. Use a piece of paper or cardboard as a bookmark.
  6. Never tear or cut out pictures/pages.
  7. Repair torn pages with paste or tape.
  8. Pack the book carefully in your school bag.
  9. Handle the book carefully when passing it to others.
  10. When first using a new book, lay it on its back and open a few pages at a time; press lightly along the binding.

Copyright and Acknowledgements

  • © 2021 Addis Ababa Education Bureau
  • Acknowledgments to Ato Zelalem Mulatu and other contributors for their leadership and input in the preparation of the textbook.

Table of Contents

  • UNIT ONE: Basics of Scientific Investigation
    • Scientific Measurements
    • Doing Scientific Investigation
  • UNIT TWO: Composition of Matter
    • Early Thinking about the Composition of Matter
    • Inside of an Atom
    • Molecules
  • UNIT THREE: Classification Of Compounds
    • Introduction
    • Organic Compounds
    • Inorganic Compounds
    • Neutralization Reaction and Salts
  • UNIT FOUR: Human Body Systems and Health
    • Integumentary System
    • Muscular System
    • Skeletal System
    • Digestive System
    • Respiratory System
    • Circulatory System
    • Reproductive System
  • UNIT FIVE: Ecosystem and Conservation of Natural Resources
  • UNIT SIX: The Solar System
  • UNIT SEVEN: Physical Phenomena in the Surroundings

UNIT ONE: Basics of Scientific Investigation

Learning Outcomes

  • Identify basic and derived units of measurements.
  • Explain measuring physical quantities.
  • Describe components of a scientific investigation.
  • Demonstrate ability to conduct fair testing.

1.1 Scientific Measurements

  • Definition: Measurement is obtaining the magnitude of a quantity relative to an agreed standard.

1.2 Doing Scientific Investigation

  • Discuss indigenous and modern methods of measurement:
    • Fundamental and derived quantities' classifications.
    • Differences between accuracy and precision.

Indigenous Methods of Measurements

  • Length: Hand-span, digit, cubit, foot, pace, arm span.
  • Mass: Weqet, Quntal, Feresula.
  • Time: Using shadows to tell time.
  • Volume: Jog, Tassa, Sini, Birchiko, Kubaya.

1.3 Examples of Measurements

  • Length: Hand-span, cubit, digit, foot, pace, arm span with their specific definitions and uses.
  • Mass: Weqet, Quntal, Feresula with their specific definitions and uses.

Accuracy and Precision in Measurements

  • Accuracy: How close a measurement is to the accepted value.
  • Precision: How consistent measurements are with one another.

Scientific Method

  1. Ask Questions
  2. Perform Background Research
  3. Establish Hypothesis
  4. Test Hypothesis
  5. Analyze Results and Draw Conclusion
  6. Communicate Results

UNIT TWO: Composition of Matter

Learning Outcomes

  • Understand historical developments in atomic theory.
  • Appreciate atomic structure's role in substances.
  • Differentiate between molecules of elements and compounds.

2.1 Early Thinking About the Composition of Matter

  • Democritus: Proposed matter consists of indivisible particles (atoms).
  • Aristotle: Believed matter is continuous and can be divided infinitely.

2.2 Inside an Atom

  • Components: Nucleus (protons and neutrons) and Electron shells.
  • Relative charges and masses of subatomic particles (proton +1, neutron 0, electron -1).

2.3 Molecules

  • Monoatomic, diatomic, and polyatomic molecules.
  • Definition: Molecule of a compound contains two or more different types of atoms.
  • Examples: Water (H2O), Ammonia (NH3).

UNIT THREE: Classification Of Compounds

Learning Outcomes

  • Define organic and inorganic compounds.
  • Classify various types of compounds.

3.1 Introduction to Classification of Compounds

  • Organic Compounds: Carbon-containing compounds (e.g., hydrocarbons).
  • Inorganic Compounds: Substances that do not primarily contain carbon (e.g., salts).

3.2 Organic Compounds

  • Hydrocarbons and their categories:
    • Alkanes (CnH2n+2)
    • Alkenes (CnH2n)
    • Alkynes (CnH2n-2)
  • Naming conventions for hydrocarbons:
    • Derived from the number of carbon atoms.

3.3 Inorganic Compounds

  • Classification into acids, bases, salts, and oxides.

UNIT FOUR: Human Body Systems and Health

Learning Outcomes

  • Identify major organs and their functions in human body systems.
  • Discuss diseases and disorders related to these systems.

4.1 Integumentary System

  • Consists of skin, hair, nails, and glands.
  • Functions: Protection, temperature regulation, sensory perception.

4.2 Muscular System

  • Types of muscles: Skeletal, Cardiac, Smooth.
  • Functions: Movement, stability, heat production.

4.3 Skeletal System

  • Functions: Support, protection, blood production.
  • Types of bones: Long, Short, Flat, Irregular.

4.4 Digestive System

  • Process of digestion and the organs involved.
  • Diseases: Constipation, Diarrhea, Gastritis, Peptic Ulcer.

4.5 Respiratory System

  • Structures: Nose, Trachea, Lungs.
  • Functions: Gas exchange, olfactory process.
  • Diseases: Asthma, Sinusitis, Influenza.

4.6 Circulatory System

  • Components: Heart, blood, blood vessels.
  • Functions: Transport nutrients, oxygen, and wastes.
  • Diseases: Hypertension, Heart Disease, Stroke.

4.7 Reproductive System

  • Male and Female organs, function, primary and secondary sexual characteristics.
  • Menstruation and Menopause.
  • STDs: HIV/AIDS, Gonorrhea, Syphilis, prevention methods.