Where students lose marks in IB Physics

Intro

After years as an IB examiner and two decades teaching the Diploma, I have come to a settled conclusion: most marks are not lost on physics. They are lost on how physics is presented. Able students — students who understand the material perfectly well — hand back answers that are correct and still incomplete, because they were never shown what the mark scheme is actually looking for. What follows is a paper-by-paper account of where those marks go, drawn from patterns I see every single season. None of it is about working harder. It is about answering the way the examination rewards.

Paper 1A: the multiple-choice booklet

Paper 1A looks like the easy part, and that is precisely where marks slip away. Three recurring habits cost students dearly.

First, blanks. There is no penalty for a wrong answer — so a blank is simply a mark thrown away. Every question must be answered, even the ones you resolve by elimination or an educated guess.

Second, the reversed question. "Which is not…", "least…", "incorrect…" — under time pressure the eye reads the familiar version and answers the opposite of what was asked. Underline the reversal every time you see it.

Third, the tempting distractor. The wrong options are not random; each is built around a common misconception. If an answer feels immediately obvious, that is sometimes the trap, not the solution. And watch the SI prefixes — a milli read as a micro turns a correct method into a wrong letter.

Paper 1B: the data-based booklet

Paper 1B rewards graph literacy, and this is where careless reading is most expensive.

The axes come first. A non-zero origin, a scale multiplier (×10³ on the axis label), or a mislabelled unit will quietly corrupt every value you read off. Check the scale before you read a single point.

Gradients are the second trap. To find a gradient, use two points far apart on the line of best fit — not two convenient adjacent data points, and not a single ratio from the origin. And remember that a gradient carries units and meaning: the gradient of a velocity–time graph is an acceleration, not "a number".

Finally, uncertainties. When a question shows error bars or asks about reliability, it wants you to engage with them. Ignoring the uncertainty when the marks are allocated to it is one of the most common ways to leave marks on the table.

Paper 2: short-answer and extended response

Paper 2 is where the gap between knowing physics and scoring in physics is widest.

The single largest source of lost marks is the command term. "State" wants a bare answer; "explain" wants a reasoned chain; "outline", "describe", "discuss" each demand a different depth. Students routinely answer at the wrong level — writing a paragraph where a line was asked, or a line where a full argument was required. The command term tells you exactly how much to write. Read it as an instruction, not a formality.

The second is missing working. In "determine", "derive" and "calculate" questions, marks are placed on the steps, not only the final number. A correct answer with no working can score less than a wrong answer with clear method. Show the substitution, the rearrangement, the units.

In the extended response, the temptation is to write everything you know about the topic. Examiners do not reward volume; they reward a connected argument. Marks land on the links — the "because", the "therefore" — that carry the physics from one step to the next. And quote your final answer to a sensible number of significant figures: more figures than the data supports is not more precise, it is a lost mark.

The three habits that cost marks everywhere

Across every paper, three small disciplines separate a 6 from a 7.

Significant figures and units. Let the data decide your significant figures, and carry units through every line. A bare number is an incomplete answer.

Command awareness. The verb governs the response. Train yourself to spot it and match your depth to it — this alone recovers marks in nearly every Paper 2.

Visible reasoning. Assume the examiner awards nothing they cannot see. If a step happened in your head, it did not happen on the page. Write it down.

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Written by an active IB Physics examiner. If your child is capable but not yet scoring the way their understanding deserves, that gap is exactly what I work on. The first step is a free consultation.

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