1. The Scientific Method and Validation
The scientific method is the process scientists use to build an accurate understanding of the world. It begins with an observation, which leads to a question. Scientists then propose a hypothesis, which is a specific, testable, and falsifiable explanation for the observation. From the hypothesis, a prediction is made about the outcome of an experiment. The experiment is then conducted, carefully controlling variables to ensure a fair test. Data is collected and analysed. If the results support the hypothesis, it gains credibility. If they refute it, the hypothesis must be revised or rejected. This process is often cyclical. A hypothesis that is repeatedly supported by a wide range of evidence may contribute to a scientific theory, which is a much broader, well-substantiated explanation for a major aspect of the natural world. Before results are accepted, they undergo peer review, where other experts in the field scrutinise the research for validity, originality, and significance. This acts as a critical quality control filter for science.
Key term
Examiner insight
Common pitfall
Fun fact
Worked example 14 marks
A student observes that plants in one corner of a garden grow taller than elsewhere. They hypothesise this is due to more sunlight. Outline the next steps they should take, following the scientific method, to test this hypothesis.
- 1
- Prediction: Formulate a specific prediction, such as 'If plants are given more sunlight, they will grow taller than plants with less sunlight, assuming all other conditions are kept the same.'
- 2
- Experiment Design: Set up at least two groups of identical plants (e.g., seedlings from the same source). Place Group A (the experimental group) in an area with high sunlight and Group B (the control group) in an area with normal or lower sunlight.
- 3
- Control Variables: To ensure a fair test, all other factors that could affect plant growth must be kept constant for both groups. These include the type and amount of soil, pot size, volume of water given, and ambient temperature.
- 4
- Data Collection and Analysis: Measure the height of all plants at the start and then at regular intervals (e.g., every three days) for a set period (e.g., four weeks). Calculate the average growth for each group and compare them to see if the results support the prediction.
Recap
- The scientific method is a systematic process for investigating phenomena.
- A hypothesis is a specific, testable explanation for an observation.
- A scientific theory is a broad, well-supported explanation built from many tested hypotheses.
- A fair test requires controlling all variables except the independent variable (the one you change) and the dependent variable (the one you measure).
- Peer review is the process where scientific experts scrutinise research before it is published.
- Scientific conclusions are always provisional and subject to change with new evidence.
Quick check
- What is the purpose of a control group in an experiment?1 mark
- What is the difference between a hypothesis and a theory?2 marks