Paper 6 (Alternative to Practical): The Complete Guide

Paper 6 is worth 20% of your IGCSE Physics grade, and students routinely drop 8-12 of its 40 marks on habits that take a week to fix. Not hard physics. Habits: units in table headings, consistent decimal places, ruled best-fit lines, named precautions. This guide covers every recurring question type and the exact phrasing mark schemes reward.

What does Paper 6 actually test?

Paper 6 tests experimental skills on paper instead of in a laboratory: reading instruments, recording data, plotting graphs, and evaluating methods. It lasts 1 hour, carries 40 marks, and follows the same structure almost every session. Knowing the theory is necessary but nowhere near sufficient.

A typical paper contains four or five questions drawn from these recurring types:

Every one of these is trainable from past papers because the mark schemes barely change between sessions.

Tables: the cheapest marks on the paper

Table questions follow three rules. Break any of them and the mark disappears even when your numbers are right.

1. Headings need quantity and unit, separated correctly. Cambridge wants “l / cm” or “t / s” style headings. A column headed just “length” loses the mark.
2. No units inside the table body. Once the unit sits in the heading, the cells contain pure numbers.
3. Consistent precision down each column. If the ruler reads to 0.1 cm, every length reads 12.0, 15.5, 18.0, never a bare 18. Raw readings match the instrument; calculated values go to 2 or 3 significant figures.

When the question asks you to take readings from pictured instruments, record to the smallest scale division. A protractor drawn to 1° means whole degrees. A stopwatch showing 22.46 s can be recorded as 22.5 s, since human reaction limits timing precision to about 0.1 s.

How do you get full marks on the Paper 6 graph?

Follow five fixed steps: label both axes with quantity and unit, choose a scale using over half the grid, plot points within half a small square, mark points with neat crosses, and draw one thin ruled best-fit line. Each step maps to a mark, and the examiner checks them in roughly that order.

The details that decide marks:

• Scales must be sensible: multiples of 1, 2 or 5. A scale of 3 units per square makes plotting errors near-certain and can lose the scale mark.
• The best-fit line balances the points, roughly equal numbers either side. It does not need to pass through the origin and must never be forced through it. It is one straight ruled line or one smooth curve, never dot-to-dot.
• Identify the anomaly. If one point sits clearly off the trend, circle it, ignore it for the line, and mention it if asked.
• Gradient from a large triangle. Use a triangle spanning more than half the drawn line, show the read-off values, and give the unit: a gradient of distance/time carries cm/s.

Our separate graphs guide goes deeper, with gradient and intercept worked examples.

Name the technique, not the intention

Method and precaution questions are where vague answers die. “Be careful”, “do it accurately” and “avoid mistakes” score zero. Mark schemes award named, physical techniques. Learn these as stock phrases:

• Repeat readings and calculate an average: the single most-awarded evaluation point.
• View the scale at eye level / perpendicular to avoid parallax error.
• Use a set square to check a rule or pendulum stand is vertical.
• Time at least 10 oscillations and divide, because reaction time is a smaller fraction of a longer measurement.
• Measure to the centre of the bob for pendulum length.
• Stir the liquid and wait for the thermometer reading to settle before recording temperature.
• Switch off the circuit between readings so heating does not change the resistance.
• Mark a fiducial point at the centre of an oscillation to judge complete swings.

When asked whether results support a conclusion, use the standard structure: calculate the relevant quantity for both data sets, compare them, then judge “yes/no within the limits of experimental accuracy”. That final phrase appears in mark schemes year after year.

Planning questions: a fill-in-the-blanks structure

The final question often asks you to plan an investigation, for 4-6 marks. Use the same skeleton every time:

1. Variables: state what you change, what you measure, and two things you keep constant.
2. Apparatus: name real equipment, including the measuring instruments.
3. Method: numbered steps, including how each quantity is measured and that readings are repeated.
4. Table: sketch the results table with headed, unit-bearing columns.
5. Graph: say what you would plot and what outcome would support the prediction.

“My school never did practicals properly, am I doomed on Paper 6?” No, and this is the paper where that matters least. Paper 6 was designed for exactly this situation, and every skill above is learnable from the last six past papers plus mark schemes. Students with weak lab experience routinely reach full marks on table and graph questions within a fortnight of drilling.

This is also one of the highest-return things to outsource. In our 1-to-1 online classes, tutors mark students’ Paper 6 attempts line by line against real Cambridge schemes, because the gap between “I knew that” and “I wrote it the creditable way” is precisely what an experienced marker spots instantly. The free 1-hour trial lesson can run a past Paper 6 question live so you see the method before paying for anything.

A two-week Paper 6 fix

If the exam is close, run this:

• Days 1-3: one table question and one scale-reading set daily, checked against mark schemes.
• Days 4-7: one full graph per day, self-marked with the five-step list above.
• Days 8-11: precaution and evaluation questions; memorise the stock phrases.
• Days 12-14: two full timed papers, 1 hour each, marked honestly.

Twenty per cent of the grade, the most repetitive paper Cambridge sets, and almost every mark trainable. Treat Paper 6 as a checklist exam and it stops bleeding marks for good.