After each series Cambridge publishes a Principal Examiner Report for every exam component. They're written for teachers, they're free, and almost no student reads them. I marked 0625 for Cambridge, and I've read every one published from 2021 to June 2026.
This post goes through the June 2026 report for Paper 6 (Alternative to Practical), variant 62. Variants 61 and 63 have their own reports. The skills are the same on all three, and the Paper 6 guide counts how many of the 17 series since 2021 each mistake appears in.
Readings and tables
“Some candidates rounded their answers to the nearest centimetre, whilst others gave answers such as 5.20 cm. This level of precision cannot be obtained when using a ruler graduated in millimetres.”
Some candidates ignored the instruction and “recorded the distance as 2 cm rather than of 2.0 cm.”
“Many candidates did not understand the meaning of the expression ‘to the nearest gram’. Common incorrect responses included 16.4 g and 17 g.”
All three are the same mark: write the reading to the precision the instrument and the question give you. On a millimetre ruler that means one decimal place in centimetres, like 5.2 cm. Read the instruction in the question, then match it.
Calculations
“Some candidates divided by 60 instead of 240 to calculate the rate of temperature increase.”
“Common incorrect responses included C / min and C° / min.” The report adds that “the instruction to give answers to 2 significant figures was frequently ignored.”
Some candidates attempted to round but recorded a value with a .0: “a calculated value of 16.4 was recorded as 16.0 instead of 16.” “Many candidates did not recognise that recording a value to the nearest ohm required an integer answer.”
Check the time you divide by against the time in the table, then the unit symbol, then the number of significant figures or decimal places the question asked for. Those three checks cover all three boxes.
Graphs
“Some candidates forced their best-fit line through the origin, although it was obvious that the plotted points would produce a line that had a sizeable y-axis intercept.”
The report's rule of thumb: “plotted dots should have diameter less than one-half of a small grid square.” It also lists scales that were “awkward to plot and check”, such as scales of 3.
Some candidates “ignored the instructions to indicate on the graph the values chosen to calculate the gradient and to show all working.” Others “inverted the gradient formula and calculated dx/dy.”
“The added portion of the line drawn often had a different gradient from the original line.”
“In graph questions, candidates should choose a scale such that the plotted points occupy at least half of the given grid.”
A neat cross is the safest way to plot a point. Draw the line through the points, not through where you expect it to go. For the gradient, mark the two points you used right on the graph and show the subtraction.
Conclusions and evaluation
“Many candidates calculated the difference between the two density values and were unable to proceed further.” The report's own method: “calculate the ratio of the smaller value to the larger value. If the ratio is 0.9 or greater, the two values may be considered equal.”
“Vague references to avoiding parallax errors, without explaining that both surfaces should be viewed simultaneously at eye level, were insufficient.”
“Many candidates referred to the relative absorbing properties of thermal radiation by the black and white cards. This was not relevant here.” The point was that the cards were at different distances from the lamp.
“The idea that, although the black card was further from the lamp, its temperature increase was still greater than that of the white card was rarely seen.”
These questions reward answering the exact situation in the experiment. Writing ‘avoid parallax’ isn't enough on its own; saying how you'd look at both surfaces at once is. And a correct fact from the topic, like black cards absorbing more radiation, was “not relevant here” when the question was about distances.
The planning question
Question 4 on this paper was timing a ball falling through oil between two marked lines on a cylinder.
“Many candidates did not state explicitly the name of the variable they had chosen to investigate.”
“Many candidates started the stopwatch when the ball was released rather than when it passed the first line marked on the cylinder.” Many also stopped it when the ball reached the bottom, not the second line.
“When the mass of the ball was the chosen variable, many candidates did not state what measuring instrument they would use.”
“Many candidates did not notice the instruction to explain how the readings would be used to reach a conclusion. Instead, they predicted how their chosen variable would affect the time taken.”
Name the variable in words. Say which instrument measures each quantity. Time exactly what the set-up describes. For the conclusion, say which graph you'd plot and what it would show, then stop. Writing what you expect to happen answers a different question.
What to do with this before the paper
1. Mark a past paper against the mark scheme, line by line. Put every lost mark under one of the five headings above. Whichever heading has the most is where your next marks are.
2. Practise the habit, not the topic. If you lost marks for rounding, the fix is reading the instruction in each question before you write the number. More revision of the topic won't help.
3. Get a second pair of eyes. You know what you meant, so you won't see the mark you didn't earn. That's what marking is for.
Sitting Paper 6 this series? I'll mark yours for £15.
Sit a past 0625 Paper 6 and send me photos of your attempt. It comes back within two days with every mark placed where you earned or lost it, and a note on each lost mark. £25 £15 until your exam. Send it by 17 October so it's back before the real paper.
Get a paper marked by a former Cambridge examiner
I marked 0625 and 9702 for Cambridge. Send me a full paper and you get it back with every mark placed, plus a note on each lost mark: what you wrote, what the mark scheme needed, and how to get it. From £25, back within a week.
See a Paper 6 I marked (shown with the student's permission, name removed).