The Most Common Mistakes in IB Maths (and How to Avoid Them)

As an IB teacher, tutor, and examiner, I have key insight into the most common mistakes students make in IB Maths exams—errors that often cost valuable marks despite being entirely avoidable. Many of these mistakes have little to do with a student’s mathematical ability and more to do with exam technique, presentation, and time management. By being aware of these pitfalls, you can maximize your score and avoid unnecessary mark losses.

1. Poor Time Management

Many students approach the exam with the “one-minute-per-mark” rule, however, this approach isn’t ideal. Some questions—like a quick differentiation problem—may only take 30 seconds, while a complex 10-mark question requires much longer. Instead of rigidly sticking to the one-minute-per-mark rule, I like to look at the total marks for each question as a whole and allocate your time accordingly. If a question is worth 10 marks, it should take proportionally longer than a 4-mark question.

A good strategy is to scan the entire paper first, tackling straightforward questions before attempting the more complex ones. If a question is taking too long, move on and come back later if time allows. Practicing under timed conditions will help you develop a better sense of how long to spend on each question.

2. Misreading the Question

Students often lose marks by simply misinterpreting what the question is asking. A problem might require an exact value, but a student provides a decimal approximation. Or, a question asks for an equation of a line, and the student only writes the gradient. Always take a moment to underline key terms like “hence,” “exact,” “simplified,” or “in terms of” to make sure you’re giving the answer in the required form.

3. Poor Notation and Presentation

In IB Maths, clarity of presentation matters. Marks are often lost due to sloppy notation—forgetting to include limits in an integral, not using proper vector notation, or omitting function notation where necessary. A particularly painful mistake is leaving off the dx in an integral, which can cost marks. The best way to avoid this is to practice writing solutions neatly and reviewing IB mark schemes to see where notation matters most.

4. Rounding Too Early (or Too Much)

The IB Maths exams specify that answers should be rounded to three significant figures, unless stated otherwise. Rounding too early in your calculations can introduce errors that compound, leading to incorrect final answers. A good rule of thumb is to carry as many decimal places as possible in your working and only round in your final answer. If you're using a calculator, store intermediate results rather than writing down rounded values.

5. Ignoring Command Terms

The IB Maths exam includes specific command terms like “show that,” “explain,” “hence,” and “justify.” Each of these words tells you how much detail is required. For example, if a question asks you to "justify" an answer, you must provide reasoning beyond just the final number. Similarly, “hence” means you should use your previous work to answer the next part. If you ignore these words, you risk losing easy marks for incomplete answers.

A common mistake students often make is to use an answer given in a "show that" question to prove the question, which scores 0 marks! Students must get the answer, from the question, and not the other way around!

6. Calculator Mishaps

While calculators are a great tool, they can also be a source of costly mistakes. Entering values incorrectly, forgetting to switch from degrees to radians, or misusing calculator functions are all common issues. To prevent this, double-check your inputs and practice using your calculator efficiently under exam conditions. Also, don’t blindly rely on it—ensure you understand the mathematical reasoning behind your answers.

There are many different calculators students can use. I recommend numworks. It is by far the easiest calculator to use, and the cheapest on the market too!

7. Skipping Steps and Not Checking Work

Under time pressure, students sometimes rush their work and skip crucial steps, leading to errors that could have been avoided. The IB mark schemes often award method marks, so even if your final answer is wrong, showing clear working can still earn you points. Additionally, leaving time to check your work—by substituting answers back into equations or verifying solutions using different methods—can catch mistakes before you hand in your paper.

Final Thoughts

The IB Maths exams are as much about strategy as they are about knowledge. By being mindful of these common mistakes and practicing exam techniques, you can maximize your score and avoid unnecessary mark losses. The key is to work neatly, use correct notation, manage time wisely, and always double-check your work. Small improvements in these areas can make a big difference on exam day.

If you’re looking for personalized support, I offer one-on-one tutoring designed to build confidence and skills at any level. Check out my tutoring services here.