Science is not just a collection of facts — it is a process of inquiry. Scientists observe the world around them, ask questions, form hypotheses, conduct experiments, and draw conclusions. This systematic approach is called the scientific method.
Key Concepts
Observation: Using our senses (or instruments) to gather information about the world. Observations can be qualitative (describing colour, texture, smell) or quantitative (measuring mass, temperature, length).
Hypothesis: A testable explanation or prediction based on observations. A good hypothesis is specific and can be proved or disproved by experiment.
Experiment: A controlled procedure to test a hypothesis. A good experiment changes only one variable at a time (the independent variable) while keeping all others constant (controlled variables) and records changes in the dependent variable.
Inference: A conclusion drawn from observations and data. Inferences explain why something happened.
Scientific tools: Rulers (length), thermometers (temperature), balances (mass), measuring cylinders (volume), stopwatches (time).
Steps of the Scientific Method
- 1.Observe a phenomenon.
- 2.Ask a question.
- 3.Form a hypothesis.
- 4.Design and conduct an experiment.
- 5.Record and analyse data.
- 6.Draw conclusions and communicate results.
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Riya notices that plants near a window grow taller than those in a dark corner. She hypothesises: "Plants grow taller when they receive more light." She sets up two identical pots, waters them equally, but places one in sunlight and one in the dark. After two weeks, she measures height. The independent variable is light; the dependent variable is height of the plant.
Arjun wants to know if salt affects the boiling point of water. He heats 500 mL of plain water and records the boiling point as 100 °C at sea level. He then dissolves 10 g of salt in 500 mL of water and heats it. He observes boiling begins at about 100.5 °C. Conclusion: dissolving salt slightly raises the boiling point.
A scientist tests three brands of paper towels to see which absorbs the most water. She dips equal-sized strips into equal volumes of water for 10 seconds each and measures water absorbed. She repeats each test three times and calculates the average. This illustrates the importance of repeated trials to improve reliability.
During a science fair, students test whether temperature affects the rate at which sugar dissolves. They use 50 mL of water at 20 °C, 40 °C, and 60 °C, add 10 g of sugar, stir for 30 seconds, and observe how much dissolves. They record results in a table — a key skill in data organisation.
A student claims "exercise increases heart rate." She measures her resting pulse, exercises for 2 minutes, then measures again. She records: resting = 72 beats/min, after exercise = 110 beats/min. Her experiment supports the hypothesis.
To compare the strength of three types of bridges (paper, cardboard, wood), a student places identical weights on each and records the maximum weight each supports before collapsing. She identifies the independent variable (bridge material) and dependent variable (weight supported).
A class investigates whether adding fertiliser increases plant growth. Two groups of identical plants are grown — one with fertiliser, one without. All other conditions (water, light, pot size, soil) are kept the same. This demonstrates the use of a control group in experiments.
Key Formulas / Relationships
- Average = Sum of all values / Number of values
- Accuracy improves with more repeated trials.
Common mistakes
Changing more than one variable at a time makes results unreliable. Always isolate the variable you are testing. Also, confusing observation (what you see) with inference (what you conclude) is a very common error.
Summary
Science uses a systematic investigative approach: observe, question, hypothesise, experiment, analyse, and conclude. Controlled experiments, accurate measurement, and repeated trials are the pillars of reliable scientific investigation.