IB Physics Exam Mistakes and How to Avoid Them
Most marks lost in IB Physics come from a small set of repeat habits, not from missing knowledge. Students round badly, misread what a question wants, give one idea where three are needed, and leave answers blank. Each of these can be fixed with practice, and this guide shows you how.
The points below draw on the examiners’ own subject reports and markschemes. We use them to build practice that targets these exact habits.
TL;DR
- Match your answer to the marks: a 3-mark question usually needs three distinct ideas.
- Keep significant figures realistic. A calculation cannot make your data more precise.
- Use all your data points when finding minimum and maximum gradients, not just the first and last.
- Never leave a multiple-choice question blank, because wrong answers are not penalised.
- Keep an error log and practise under exam conditions until the slips stop.
Table of Contents
- Mistakes with data, uncertainties and graphs
- Mistakes with calculations, units and powers of ten
- Mistakes in reading the question
- What the markscheme actually rewards
- Mistakes in timing and presentation
- A practice routine that fixes these habits
- Practise the way the exam tests you
- FAQ
- Sources
Mistakes with data, uncertainties and graphs
The May 2025 TZ2 Physics subject report lists several recurring data-analysis errors. They include unrealistic significant figures, confusing proportional with linear, confusing speed with velocity, and forcing a linear fit without justification. Failing to justify outliers is on the list too.
The same report notes that when repeated measurements do not vary, the minimum uncertainty is the least count, not zero.
Gradients and error bars
The May 2024 TZ1 report says nearly all students used only the first and last data points to find minimum and maximum gradients. All data points need to be considered. It also says a coefficient of linear correlation is irrelevant when each datum has experimental uncertainty.
A better routine:
- Plot every point with its error bars.
- Draw the best-fit line through the bars.
- Draw the steepest and shallowest lines that still pass through all the bars.
- Calculate both gradients and quote the uncertainty from them.
Significant figures
The May 2025 report says calculations cannot improve precision. Round addition and subtraction to the least precise number of decimal places. Round multiplication and division to the least precise number of significant figures. The report also notes that some students fill several pages with simple calculations such as averaging repeated measurements. Keep these short.
Mistakes with calculations, units and powers of ten
The IB Physics guide expects you to apply SI prefixes and units and to use the symbols from the guide and data booklet. Neglected units and powers of ten can disrupt fluency and lead to bigger errors later.
The May 2024 TZ1 report adds that relying on a calculator for simple cancelling of powers of ten wastes time. It can also cause panic when a calculation appears. Practise handling powers of ten by hand, quickly.
A quick check before you move on:
- Do the units on both sides of the equation match?
- Is the prefix converted (mm to m, kHz to Hz)?
- Is the size of the answer sensible for the situation?
The May 2025 Paper 2 SL markscheme says candidates are not penalised for unit or significant figure errors unless the Notes column refers to them. That is no reason to be careless. Wrong units are often the first sign of a wrong method, and a wrong method costs marks.
Mistakes in reading the question
The November 2025 TZ1 report points out that students sometimes answer multiple-mark questions with single statements. A 3-mark question generally needs 3 distinct ideas. It also warns against spending time rewriting the prompt.
On multiple choice, the same report notes that all four options may correctly describe the situation. Your job is to pick the one that directly explains, causes or follows from the information given. It also reminds students to check the scope of the equations in the data booklet.
The May 2024 report suggests stepping back first. Picture what is happening and name the core physics before you dive into the data booklet. Its other tips include:
- Eliminate clearly wrong options.
- Consider units.
- Exaggerate a variable.
- Draw the situation.
- Check cos, sin and tan by imagining the angle at 0° or 90°.
- Read the axes on graphs.
What the markscheme actually rewards
A common worry is whether a correct answer with different working still scores. The May 2025 Paper 2 SL markscheme says a correct numerical answer with no working earns full marks unless the Notes say otherwise. If the physics or method is wrong, a correct answer is treated as numerical coincidence and penalised.
The same markscheme says equivalent answers can earn marks. Marking points need not appear in the markscheme’s order unless the Notes say so. It also awards error carried forward (ECF) when an incorrect answer is used correctly later.
So show your method clearly. Even if an early part goes wrong, later parts can still score.
Mistakes in timing and presentation
The November 2025 report says blank responses were similar at both levels. That suggests some students ran out of time and others skipped questions they were unsure about. It reminds students that incorrect answers are not penalised, so make an educated guess.
It also warns that students sometimes wrote outside the scanned boxes. Examiners try to find off-scan work but are not responsible if unidentified material goes unmarked. Ask for an extra booklet if you need space, and write the question number and section at the start of each answer.
A practice routine that fixes these habits
Rereading notes feels productive but does not show readiness. Replace some of it with attempted questions, then mark them against the scheme. Keep an error log, sorted by type: units, rounding, command terms, signs, graphs. Review it weekly and watch which categories keep returning.
One student-written study schedule describes a weekly error log. Its author also aimed for 5 to 7 full past papers per HL subject in the six months before finals. Treat that as one example, not a rule.
Our perspective
We build Tiber Tutor with IB examiners and experienced educators, and the same slips appear year after year. Students who know the content still lose marks on rounding, on thin answers to multi-mark questions and on graph work. That is why we link every resource to the others. A question you get wrong points you to the notes and animated videos for that topic, and your answers are checked against examiner mark schemes in our student-led review.
Our progress tracking and performance analytics show which topics and question types cost you marks, so your error log builds itself. We are not aware of another IB STEM platform that joins these pieces together, and we believe it offers the best value for money because actual IB examiners write the content. You get polished, exam-style material in one place, with a clear picture of where to improve.
Oliver
Practise the way the exam tests you
Our platform gives IB Physics students exam-style questions, animated videos, notes, flashcards, cram sheets, topic tests and mock exams, all written by IB examiners. Our IB Physics mock exams let you rehearse timing and layout. The exam breakdown shows what each paper expects. With the custom test builder, you can drill the topics where your log shows repeated slips.
Every plan starts with a free 7-day trial. After that, the Per-Subject Plan is $9 per month and the All-Access Plan is $19 per month. See the plans and pricing to choose one. Parents can read more on our page for IB parents.
FAQ
Do I get full marks for a correct answer if my method differs from the markscheme?
Usually yes, if your physics is valid. The May 2025 Paper 2 SL markscheme says a correct answer with no working earns full marks unless the Notes say otherwise. A wrong method makes a correct number a coincidence, and it is penalised.
Should I guess on multiple-choice questions?
Yes. The November 2025 subject report reminds students that incorrect answers are not penalised. Eliminate options you know are wrong first, then make an educated guess rather than leaving a blank.
How many significant figures should I give?
No more than your least precise data allows. For multiplication and division, use the fewest significant figures in your inputs. For addition and subtraction, use the fewest decimal places.
What is the quickest way to improve?
Do timed questions, mark them against the scheme and log each error by type. Then target the types that recur with a custom test. Little and often works better than one long session.
Sources
- IB Physics subject report, May 2025 TZ2
- IB Physics guide, first assessment 2025
- IB Physics subject report, May 2024 TZ1
- IB Physics subject report, November 2025 TZ1
- Physics Paper 2 SL markscheme, May 2025
- The Study Schedule That Earns Top Grades