Thinking Like a Scientist
2. Asking Scientific Questions
Learning outcomes
- I can identify questions that can be investigated scientifically.
- I can distinguish between testable and non-testable questions.
- I can write clear, focused scientific questions.
- I can identify variables within a scientific question.
- I can refine scientific questions to improve investigations.
Introduction
Every scientific investigation begins with a question.
Some questions can be answered by carrying out experiments or making observations. Other questions cannot be answered scientifically because they involve opinions, personal preferences, or beliefs.
Learning to ask good scientific questions is an important skill. A well-written question helps scientists plan fair investigations, collect useful evidence, and draw reliable conclusions.
Great scientific discoveries often begin with simple questions, such as:
- Why do plants grow toward light?
- What causes rainbows?
- How does temperature affect the rate of a chemical reaction?
What Makes a Scientific Question?
A scientific question is one that can be answered by:
- making observations
- collecting evidence
- carrying out investigations or experiments
Scientific questions focus on the natural world.
Examples:
- Does fertilizer affect plant growth?
- How does temperature affect the solubility of sugar?
- Which material is the best thermal insulator?
These questions can all be investigated using evidence.
Testable and Non-Testable Questions
Not every question can be investigated scientifically.
Testable Questions
A testable question can be answered by collecting evidence.
Examples:
- Does sunlight affect the growth of bean plants?
- How does the length of a pendulum affect its period?
- Which paper towel absorbs the most water?
Non-Testable Questions
A non-testable question cannot be answered through scientific investigation.
Examples:
- Which colour is the most beautiful?
- Which pet is the best?
- Is chocolate the tastiest food?
These questions depend on opinions or personal preferences rather than evidence.
Characteristics of a Good Scientific Question
A good scientific question is:
- Clear
- Specific
- Focused
- Testable
- Measurable
Good questions identify exactly what will be investigated.
For example:
Instead of asking:
"How do plants grow?"
Ask:
"How does the amount of sunlight affect the height of bean plants over three weeks?"
The second question is much more specific and easier to investigate.
Variables in Scientific Questions
Most scientific investigations involve variables.
A variable is something that can change during an investigation.
There are three main types.
| Variable | Description |
|---|---|
| Independent Variable | The factor that is changed by the investigator. |
| Dependent Variable | The factor that is measured or observed. |
| Controlled Variables | Factors that are kept the same to ensure a fair test. |
Example
Question:
How does the amount of water affect the height of bean plants?
Independent variable:
Amount of water
Dependent variable:
Height of the plant
Controlled variables:
- Type of plant
- Soil
- Pot size
- Amount of sunlight
- Temperature
Identifying variables helps scientists design fair and reliable investigations.
Refining Scientific Questions
Sometimes a question is too broad.
For example:
"How does exercise affect people?"
This is difficult to investigate.
It can be improved by making it more specific.
For example:
"How does 20 minutes of daily running affect the resting heart rate of teenagers after four weeks?"
The refined question clearly states:
- what is changing
- what is being measured
- who is being investigated
- the time period
This makes it much easier to design an investigation.
Examples of Refining Questions
| Broad Question | Improved Scientific Question |
|---|---|
| How do plants grow? | How does fertilizer affect the height of tomato plants over four weeks? |
| Which paper is best? | Which type of paper towel absorbs the most water? |
| Does temperature matter? | How does water temperature affect the time required for sugar to dissolve? |
| Which battery lasts longer? | Which brand of AA battery powers an LED flashlight for the longest time? |
Why Scientific Questions Matter
A well-designed scientific question helps scientists:
- plan investigations
- identify variables
- collect useful data
- draw valid conclusions
- communicate their research clearly
Without a clear question, an investigation may become confusing or produce unreliable results.
Real-World Applications
Scientists ask investigable questions in many fields, including:
- Medicine
- Environmental science
- Engineering
- Agriculture
- Astronomy
- Physics
- Chemistry
- Biology
Every new scientific discovery begins with someone asking an interesting question.
Worked Examples
Example 1
Is the following question testable?
Does sunlight affect the growth of plants?
Answer:
Yes.
The amount of sunlight can be changed, and plant growth can be measured.
Example 2
Is the following question testable?
Which season is the nicest?
Answer:
No.
The answer depends on personal opinion.
Example 3
Identify the independent variable.
Question:
How does temperature affect the rate at which sugar dissolves?
Answer:
Temperature
Example 4
Identify the dependent variable.
Question:
How does the amount of fertilizer affect plant height?
Answer:
Plant height
Example 5
Rewrite the question to make it more specific.
Original question:
How does exercise affect health?
Possible answer:
How does 30 minutes of cycling each day affect resting heart rate in teenagers after six weeks?
Did You Know?
In 1928, Alexander Fleming noticed that bacteria were not growing near a type of mould in one of his laboratory dishes. Instead of ignoring this unusual observation, he asked a scientific question about it. His investigation led to the discovery of penicillin, the world's first widely used antibiotic, which has saved millions of lives.
Key Terms
| Term | Definition |
|---|---|
| Scientific Question | A question that can be investigated using observations, experiments, and evidence. |
| Testable Question | A question that can be answered by collecting measurable evidence. |
| Variable | A factor that can change during an investigation. |
| Independent Variable | The variable that is deliberately changed. |
| Dependent Variable | The variable that is measured or observed. |
| Controlled Variables | Factors that are kept the same to ensure a fair test. |
| Fair Test | An investigation in which only the independent variable is changed while all other relevant variables are controlled. |
Key Takeaways
- Every scientific investigation begins with a clear question.
- Scientific questions must be testable using evidence from observations or experiments.
- Testable questions differ from questions based on opinions or beliefs.
- Identifying independent, dependent, and controlled variables helps scientists design fair investigations.
- Refining broad questions into specific, focused questions improves the quality of scientific investigations.
- Asking good scientific questions is the first step toward making new scientific discoveries.