How to Write Your IB Biology Internal Assessment

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Performing well on the IA requires careful planning, research, experimentation, analysis, and writing. In this guide, we will walk you through the key steps to write your IB Biology Internal Assessment.

After all, the internal assessment (IA) is a crucial part of the IB Biology curriculum, accounting for 20% of your final grade.

What is the Biology Internal Assessment?

The IB Biology IA is an independent investigation into a topic of your choice related to biology.

Your task is to design, conduct, analyse, and describe your experiment in detail. Typically, it takes around 10 hours of class time to work on the IA, but you will likely need to put in additional time outside of class.

The final paper should be between 6 and 12 pages long. A solid, well-designed IA can bring you a maximum of 24 points.

To ensure you have exactly that, don’t hesitate to use our guide on how to write your IB Biology IA. If you get stuck our IB Biology tutors, all IB Biology Teachers, and Examiners can help.

Choosing a Research Question

The first step is to choose a focused research question on a biological topic that interests you. The question should be specific enough to investigate through an experiment in the time available. Now sure which topic to use? Here are a few great IB Biology IA ideas.

Planning the Experiment

Once you have a research question, plan out how you will investigate it through an experiment. It is vital to consider the variables you will measure and control, the materials and methods you will use, and the data you aim to collect. Your teacher must approve your plan before you begin.

IB Biology Student Researching IA

Conducting the Experiment

You need to carry out your experiment safely and systematically. Every observation and data you obtain should be carefully recorded. It is important that you repeat your experiment to verify results and possibly find any errors and omissions in your methodology.

Analysing and Concluding

Examine your data and use statistics to identify patterns and relationships. This data will help you draw conclusions to answer your original research question. For the best marks, you ought to discuss sources of error and suggest improvements for further investigation.

How to Write IB Biology Internal Assessment

When writing the IB Biology Internal Assessment, you need to follow the required structure to demonstrate your scientific skills. Here are our extensive guidelines for each section of your paper.

The Title and Contents Pages

The Title Page sets the tone for the entire paper. Your goal is to craft a descriptive title that reflects the purpose of the study. For example, “An Investigation into the Effect of X on Y.”

The title must be accompanied by a focused research question involving the key variables.

The Contents Page outlines the IA’s structure. It lists all sections and page numbers so readers can easily navigate the document.

Taking time with these initial pages will show your ability to be organised and thoughtful. The title and contents provide the first impression to evaluators. Therefore, you need to refine them to reflect the quality of work that follows.


This section covers your investigative question, hypothesis, variables, procedures, and data collection plans.


Phrase your research question clearly and specifically. It should be focused enough to be thoroughly tested experimentally. If your experiment involves a living organism, you must identify it by both common name and scientific name (genus and species). On top of that, you should also specify units, time, and location, if applicable.


First, state your actual hypothesis. This should be a testable prediction about the anticipated results. Next, provide 2-3 sentences explaining your rationale. Link it logically to scientific principles and cite any research that informed your hypothesis. Your conclusion will either support your hypothesis or reject it.


Make a tidy table with columns labelled “Independent”, “Dependent”, and “Controlled Variables”. The independent variable is what you intentionally manipulate – be highly specific about the increments tested. The dependent variable is what changes in response and is measured. Controlled variables are held constant to isolate effects. In your Internal Assessment, you need to list at least 5 controls and 15 repeats.

Protocol Diagram

Draw and fully label a visual diagram of your experimental setup, especially detailing how the independent variable was implemented. For example, if testing temperature, show the water bath or incubator set at different temperatures. Highlight any differences between control and experimental groups.

Lab Setup Photo

Take a photo of your actual lab setup and annotate it to illustrate how you obtained variables. By doing so, you verify that you followed your planned methodology. Don’t forget to specify all the apparatus, solutions, and chemicals you used for your experiment.

Preliminary Experiment

The Preliminary Experiment provides critical insights that guide the main investigation. In this section, you need to explain how it shaped your methodology, analysis approach, and decision-making. If a preliminary experiment was not conducted, you need to research the independent variables and the method for measuring the dependent variable. This analysis will mimic the function of a preliminary experiment in informing the main investigation’s design.


This part involves writing the experimental procedure in clear numbered steps. You can use passive voice to make it look like an instruction. Make sure to include enough detail so that someone can repeat the process. You need to include at least 5 increments of your independent variable (e.g. 5 temperatures) and a minimum of 5 trials/replicates per increment. Please keep in mind that your procedure should collect both quantitative data (numbers) and qualitative data (observational descriptions).

Data Collection

Data Tables

This section of your Internal Assessment should include at least 3 data tables:

  • Raw Data Table features only unprocessed numbers;
  • Control Variables Table, which presents values of controlled variables, for instance, initial temperatures;
  • Qualitative Data Table including observational descriptive details.

You need to give all these tables clear, descriptive titles. It is also essential to label all your columns with headings and units of measurement. You are at risk of losing marks if you miss even a single unit.

Data Formatting and Layout

You shouldn’t start your table on one page and continue on another. However, if you have a large table that doesn’t fit into one page, you should repeat the title and column names after the split.

If your data is likely to come with uncertainties (for example, human reaction time), you can specify them in footnotes. You should also indicate equipment precision in column headings.

Biology Internal Assessment Analysis

Your analysis section should show how you have used both qualitative and quantitative methods to support your arguments, and how you have identified and justified any discrepancies or errors in your data.

Sample Calculation

Pick one sample of processed data to explain your calculations. You need to show the equation you used as well as track each step to demonstrate how you converted raw numbers into analysed data.

Processed Data & Graphs

This section of your IB Biology Internal Assessment presents data tables of your calculated/processed data. Use formats appropriate for the type of data (for instance, bar, line, or scatter plots) to create 1-2 graphs. All graphs should have titled axes with units and a figure legend. It is more than likely that your data will feature uncertainties and errors – don’t try to hide them. In fact, you need to demonstrate them. Best-fit lines and error bars can help you indicate these uncertainties and deviations.


Here, you need to explain whether your results support or reject your original hypothesis. Refer directly to data points and figures to substantiate your scientific argument. You can’t simply state that the hypothesis was proven. Instead, you need to point out whether your data was consistent or inconsistent with the hypothesis.


Identify at least 3 weaknesses or challenges in your experimental design, such as a lack of controls or a limited number of trials. Explain how each limitation impacts the quality and interpretation of your results.

If you provided error bars, you need to explain what they demonstrate.

Suggestions for Improvement

Propose at least 3 changes to improve the quality of your experimental design and data produced if repeated. Those can include additional controlled variables, more replicates, different measurement techniques, increased precision on equipment, etc. Explain how each suggestion would specifically refine the experiment.

Conclusion of Your Biology Internal Assessment

This section summarises the results of your experiment and answers your research question. You should also link your findings to theories and scientific principles.


The final part of your IB Biology IA is a list of all the sources you utilised in your experiment (textbooks, research, academic papers, etc.). You need to use the citation style recommended by your school.

Need Help with Writing Your IB Biology Internal Assessment?

With 20% of your total grade, IB Biology Internal Assessment is a crucial aspect of your academic journey. It’s an opportunity to demonstrate your skills and understanding to both yourself and your assessors. To ensure an IA paper, you need to approach it with dedication, thoroughness, and a commitment to scientific excellence.

This journey can be quite stressful, but you don’t have to face it alone. At TutorsPlus, we understand the significance of your Internal Assessment and are here to support you every step of the way. Whether you need assistance in selecting the perfect topic, refining your methodology, or reviewing your written report, our knowledgeable IB Biology tutors are ready to guide you towards success.

Don’t hesitate to reach out to us for expert help and guidance. We are available at +41 022 731 8148 or With TutorsPlus by your side, you can turn your Internal Assessment into a remarkable achievement.


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