The Internal Assessment (IA) can be a game-changer in your final IB grade—but it’s also where many students make preventable mistakes. From unclear research questions and weak hypotheses to missing control variables or incomplete data tables, it’s easy to lose marks if you don’t fully understand the IB’s assessment criteria. One of the most common errors is choosing a topic that’s too ambitious or too simple—both of which can limit your analysis. Another red flag is vague evaluations that don’t explain limitations or errors in enough depth. Many students also underestimate the importance of citing sources properly, which can affect both your marks and academic integrity.
In this blog post, we walk through the top 10 mistakes we see in Chemistry and Biology IAs, based on real student submissions we’ve reviewed. For each mistake, we also give you a clear fix—whether it’s adjusting your research question, refining your methodology, or enhancing your evaluation section. These insights are based on years of IB tutoring and examiner feedback. If you’re currently writing or revising your IA, this post is a must-read. And if you need extra support, our tutors at TutorTide HK offer 1-on-1 IA coaching sessions to help you polish your work before submission.