You’ve collected your data. You’ve survived the experiment. Now comes the part that trips up even the strongest students: writing the report.
Most students lose marks not because their physics is wrong, but because their report is structured badly. The examiner can’t find what they’re looking for. Marks slip through the gaps.
This post gives you the exact 13 subtitles to use in your IB Physics Scientific Investigation, in the correct order, with a clear explanation of what belongs in each one. Follow this structure and you give yourself the best possible chance of full marks on every criterion.
Your report structure is not a creative choice. It is a mark-earning tool. Use the one that works.
If you haven’t chosen your topic yet, start with my list of 100 IB Physics IA ideas before you come back here.
The 13 Subtitles to Use
In order:
- Introduction
- Research Question
- Theory and Hypothesis
- Variables
- Diagram
- Apparatus
- Method
- Raw Data
- Processed Data
- Graph
- Analysis and Conclusion
- Evaluation
- References
That’s it. Use these as your headings, in this order, and your report will be easy for an examiner to navigate. Easy to navigate means easy to award marks.
Let me walk you through each one.
1. Introduction
Brief. Focused. Purposeful.
Your introduction should explain the thought process behind choosing this topic. Not your passion for it. Not your life story. Just a clear, concise explanation of why this investigation is worth doing.
Two or three short paragraphs is plenty. I go into the exact five sentences to include in a separate post on writing a perfect IA introduction, but the key point is this: don’t pad it out. Examiners read hundreds of IAs. They reward clarity.
Do not include a title page. Your IA does not need one.
2. Research Question
This gets its own subtitle for a reason. A clearly labelled Research Question tells the examiner exactly what you’re investigating and signals that your report is well-organised from the start.
In most cases, your research question should follow this format:
How does [Variable X] affect [Variable Y]?
It should be specific, measurable, and answerable within the scope of your experiment.
If you’re still working out what your research question should be, my post on 100 IB Physics IA ideas will help you find a topic with a natural, testable question built in.
3. Theory and Hypothesis
This is where you explain the physics behind your research question, then use that theory to make a prediction about your results.
The biggest mistake most students make here is including too much background physics that has nothing to do with their research question. More is not better. Relevant is better.
Keep the theory tightly focused on the relationship you’re actually investigating. If your investigation is about capacitor discharge, you need the equation for exponential decay. You do not need three pages on the history of electricity.
Your hypothesis should predict a mathematical relationship if possible. These are two good examples of what that looks like:
- The length of the lasso will be directly proportional to the square of the time period.
- The voltage across the capacitor will decay exponentially with time.
You should include a hypothesis. Some students skip it thinking it’s optional. It is not. The examiner expects a prediction, and your conclusion will be judged against it.
A sketch graph showing your expected result is a nice touch here too.
4. Variables
A short, clearly labelled section. Just write down:
Independent Variable: the variable you are changing (Variable X)
Dependent Variable: the variable you are measuring (Variable Y)
Control Variables: everything you are keeping constant to make it a fair test.
Don’t over-explain. One or two sentences per variable is enough.
5. Diagram
Include a labelled diagram showing how your apparatus is set up. It does not need to be a work of art. It needs to be clear enough that someone could look at it, look at your apparatus list, and set the experiment up themselves.
I recommend Google Drawings for this. It’s free, simple, and produces clean diagrams quickly.
6. Apparatus
A bullet point list of everything you used. Keep it simple. Include the measurement range and uncertainty of any measuring instruments (for example, “ruler, 30 cm, ± 0.5 mm”).
That’s all this section needs to be.
7. Method
A numbered list of steps. Aim for no more than ten. The key principle is the same as the diagram: write it so that someone intelligent who has never done your experiment could follow it.
Do not include steps like “set up the apparatus” or “collect the sellotape”. Treat the reader as capable of looking at your diagram and getting started. Your method should cover the actual procedure, safety considerations, and how you ensured a fair test.
8. Raw Data
Your raw data table goes here. A few important rules:
- Include only the data you actually collected. No processing yet.
- Include the reading error (uncertainty) for each measurement in the column header.
- If you need to justify the reading error, a single sentence underneath the table is enough.
Do not include appendices. There is no appendix in an IB Physics IA. If you have a lot of data, find a way to represent it clearly and concisely in the main report. Screeds of data hidden at the back will not be marked.
9. Processed Data
A separate data table showing your calculations. This might include averages, combined uncertainties, squared values, or whatever manipulation your analysis requires.
Label every column clearly with the quantity and unit. Show an example of each calculation you performed underneath the table. One worked example per calculation type is sufficient.
10. Graph
Plot your graph here. Hand-drawn on graph paper is completely acceptable if you’re struggling with graphing software. The examiner does not penalise you for this.
That said, graphing software is genuinely useful for:
- Finding the line of best fit
- Determining the mathematical relationship between your variables
- Calculating the gradient and intercept with uncertainty
- Drawing error bars and max/min lines cleanly
Aim to linearise your data so you can plot a straight line graph. If your relationship is proportional to the square of a variable, plot the square.
11. Analysis and Conclusion
This is where you pull everything together. A good Analysis and Conclusion section should include:
- A brief recap of your hypothesis
- A description of the pattern shown in your graph
- Whether the line of best fit passes through the origin, and whether you expected it to
- Whether your results support your hypothesis
- A comment on the uncertainty in the gradient and what it tells you about reliability
- A comment on the spread of data points
- Any anomalies (circle them on the graph and explain them)
- A quantity calculated from the gradient if possible (for example, gravitational field strength, a specific heat capacity, a spring constant)
- Any systematic error suggested by a consistent intercept on an axis
Work through this list carefully. Many students write a decent experiment and then lose marks here because their conclusion is thin.
12. Evaluation
Most students run out of energy here, and it shows. The Evaluation section is where marks are consistently dropped.
Writing “carry out more trials” or “use a more accurate ruler” is not enough. These are weak, generic improvements. The examiner wants to see that you understand the specific limitations of your experiment and can suggest targeted, meaningful improvements.
Aim for three weaknesses, structured like this for each one:
- What the weakness is
- How significant it is (did it affect your results by a lot or a little?)
- A specific, realistic improvement
If your temperature control was inconsistent because you used a beaker of hot water that cooled during the experiment, say that. Then suggest using a temperature-controlled water bath as a specific improvement. That’s the kind of response that earns marks.
13. References
List any sources you used. The Harvard referencing style is the standard choice for IB students.
One Final Thing: Length
Your completed IB Physics Scientific Investigation should be around 12 word-processed pages and contain fewer than 3,000 words.
That limit is tighter than students expect. Every word needs to earn its place. This is not an essay. It is a scientific report. Precision and clarity are what examiners reward.
Still looking for a topic to investigate? My post on 100 IB Physics IA ideas organised by theme covers every part of the current IB Physics syllabus, with ideas at every level of difficulty.
And if you want topic-by-topic past paper questions, revision note templates, and a full mock exam to practise with once your IA is done, the Exam Pack has everything you need to finish the course strong.
Get the GradePod Exam Pack for £39 →
Written by Sally Weatherly, IB Physics teacher since 2004, Fellow of the Institute of Physics, and founder of GradePod. I help students work smarter, not harder.