Introduction
In the sciences — Biology, Chemistry, and Physics — the Internal Assessment (IA) is built around experiments. A well-designed experiment can make your IA stand out, while a weak or poorly controlled one can lower your marks even if your writing is strong. Examiners want to see that your experiment is clear, replicable, and scientifically valid.
In this guide, we’ll explain how to design effective experiments for a science IA, including tips for choosing a research question, controlling variables, collecting data, and evaluating results. For models of strong experimental IAs, you can review RevisionDojo’s coursework exemplars.
Quick Start Checklist: Effective Science IA Experiments
- A clear, testable research question
- Identification of independent, dependent, and controlled variables
- Sufficient data collection through multiple trials
- Use of reliable equipment and consistent methods
- Consideration of errors, ethics, and limitations
Step 1: Start With a Testable Research Question
The foundation of any science IA experiment is a question that is:
- Specific: Focused on one independent and one dependent variable.
- Feasible: Possible to test with available resources.
- Relevant: Linked to scientific concepts in the syllabus.
Examples:
- Biology IA: “How does light wavelength affect the rate of photosynthesis in pondweed?”
- Chemistry IA: “How does concentration affect the rate of reaction between hydrochloric acid and magnesium?”
- Physics IA: “How does the angle of release affect the range of a projectile?”
Step 2: Define Variables Clearly
Every science IA experiment must identify:
- Independent variable: The factor you change (e.g., temperature).
- Dependent variable: The factor you measure (e.g., reaction rate).
- Controlled variables: Factors kept constant to ensure fairness (e.g., volume of solution, same species of plant).
Examiners expect explicit acknowledgment of these.
Step 3: Ensure Replicability
An effective experiment must be replicable. Examiners ask: Could another student repeat this experiment and get similar results?
- Write procedures step by step.
- Include details about equipment, units, and measurements.
- Use diagrams where necessary.
Replicability adds scientific credibility.
Step 4: Collect Sufficient Data
Strong science IAs require robust data. Weak experiments often fail because of too few trials or small sample sizes.
- At least 5–10 data points for each independent variable.
- 3–5 repeated trials to reduce random error.
- Use averages, standard deviation, or error bars to process results.
Examiners reward reliability over speed.
Step 5: Use Appropriate Equipment
Choose equipment that minimizes errors and produces accurate data. For example:
- Use a digital timer instead of a phone stopwatch.
- Use precise measuring tools like burettes instead of beakers for liquids.
- Calibrate instruments where possible.
Better equipment improves the reliability of your IA.
Step 6: Anticipate Errors and Limitations
No experiment is perfect. Examiners value awareness of limitations, such as:
- Random errors (e.g., variations in reaction times).
- Systematic errors (e.g., faulty equipment).
- Environmental factors (e.g., light fluctuations in biology experiments).
Acknowledging limitations — and suggesting improvements — strengthens your IA evaluation.
Step 7: Keep Ethics in Mind
Science IAs must follow ethical guidelines. For example:
- Avoid harming animals or humans.
- Use safe concentrations of chemicals.
- Dispose of materials responsibly.
Ignoring ethics can lower marks and cause issues with approval.
Common Mistakes in Science IA Experiments
- Choosing topics too broad or impossible to test.
- Collecting too little data to analyze meaningfully.
- Failing to identify controlled variables.
- Using vague or incomplete methods.
- Ignoring errors and limitations in evaluation.
Why Exemplars Are Helpful
If you’re unsure how detailed your experiment design should be, look at strong examples. RevisionDojo’s coursework exemplars showcase science IAs where experiments are well-designed, controlled, and examiner-ready.
FAQs on Science IA Experiments
1. How complex should my science IA experiment be?
It doesn’t need to be overly complex — examiners value clarity and reliability over sophistication.
2. Do I need to use advanced equipment?
Not necessarily. Simple experiments done carefully often score higher than advanced ones with poor execution.
3. How do I decide how many trials to run?
Aim for at least 3–5 trials per condition. More trials increase reliability.
4. Should I include raw data in the IA body?
Only processed data should be in the main body. Raw data belongs in appendices.
5. Where can I see examples of strong science IA experiments?
Check RevisionDojo’s coursework exemplars, which highlight successful experimental setups.
Conclusion
Designing an effective experiment is the foundation of a high-scoring science IA. By starting with a testable research question, defining variables, ensuring replicability, collecting sufficient data, using reliable equipment, acknowledging errors, and following ethical standards, you’ll create an IA that impresses examiners. To see real examples, explore RevisionDojo’s coursework exemplars.
Call to Action
Want to design a science IA experiment that stands out? Explore RevisionDojo’s coursework exemplars today and learn from high-scoring student investigations.
