Grade 8 General Science Note

2. Scientific Measurements
2.1 Introduction to Measurement
Measurement involves comparing a quantity to a standard using a numerical value and a unit (e.g., 32 kg).

2.2 Indigenous Methods of Measurement

• Length:

  • Hand-span: Tip of thumb to little finger.

  • Cubit: Elbow to tip of middle finger.

  • Pace: One walking step.

  • Arm span: Fingertips with arms outstretched.

• Mass:

  • Weqet: Small quantities like gold powder.

  • Quntal: Grains, equal to 100 kg.

• Time:

  • Observed by shadow length changes as the Sun moves.

• Volume:

  • Jog: Measures liquids.

  • Tassa: For cereals and liquids.

2.3 Scientific Measurements

• Physical Quantities:

  • Fundamental Quantities: Cannot be derived (e.g., mass, length).

  • Derived Quantities: Formed by combining fundamental quantities (e.g., area, density).

• SI Units:

  • Length: Meter (m).

  • Mass: Kilogram (kg).

  • Time: Second (s).

  • Temperature: Kelvin (K).

• Prefixes:

  • Mega (M): 1,000,000

  • Kilo (k): 1,000

  • Milli (m): 0.001

2.4 Measurement Tools

• Mass: Balances (spring, digital).
  1 kg = 1,000 g.

• Length: Rulers, tapes.
  1 m = 100 cm = 1,000 mm.

• Time: Clocks, stopwatches.
  1 hour = 60 minutes.

• Temperature: Thermometers (analog, digital).

Conversions Examples:

• Convert 6.5 kg to g:
  6.5 × 1000 = 6500 g.

• Convert 200 m to km:
  200 / 1000 = 0.2 km.

3. Accuracy and Precision

• Accuracy: Closeness to the true value.

• Precision: Consistency among repeated measurements

4. Scientific Method
Science is a process of learning about the world through observation, inquiry, formulating and testing hypotheses, gathering and analyzing data, and reporting and evaluating findings. This process is called the scientific method.

Steps of the Scientific Method:

• Ask Questions: Begin with observations leading to a measurable and answerable question.

• Perform Background Research: Conduct preliminary research to understand previous work on the topic.

• Establish a Hypothesis: A logical, testable explanation of the observations, including predictions.

• Test the Hypothesis: Conduct experiments to test the hypothesis, ensuring consistency and fairness.

• Analyze Results and Draw Conclusions: Determine if the hypothesis is supported by the results. If not, revise the hypothesis and test again.

• Communicate Results: Share findings with others through reports or presentations for verification and further exploration.