Paper 3 Answering Technique

Structure of Paper 3

Paper 3 tests science process skills through two sections. Section A is based on a described experiment or a set of given data, such as a diagram, table, or set of readings, and asks a series of guided questions that build up to a conclusion.

Section B gives a problem statement, hypothesis, or set of materials, and requires you to plan a complete experiment from start to finish.

Approaching Section A step by step

1. Read the given information carefully, including any diagrams, apparatus described, and the data provided, before attempting any question.
2. State the manipulated, responding, and controlled variables clearly, using the exact terms and units given in the question.
3. Complete any table by following the rules for headings, units, and consistent decimal places.
4. Plot any graph accurately, choosing an appropriate scale and drawing a line or curve of best fit.
5. Write a conclusion that directly answers the aim, referring to the actual trend shown in the data, and state whether the hypothesis is accepted or rejected.
6. For evaluation questions, comment on the reliability of the method, suggest a precaution, or propose an improvement, always linking your answer to the specific experiment described.

Approaching Section B step by step

Section B requires a full plan, in order: aim, hypothesis, variables (manipulated, responding, controlled), a complete list of apparatus and materials, and a numbered, detailed method that includes how the responding variable will be measured, how the manipulated variable will be varied, and how the results will be tabulated. State clearly how the experiment will be repeated for reliability, and include a control setup where relevant.

Marks and precision

Marks in Paper 3 are awarded for precise, specific answers rather than general statements. State variables with their units, use exact figures from the data rather than vague descriptions like 'increases a lot', and make sure every step of a planned method is detailed enough for someone else to carry it out exactly as intended.

Science process skills tested

Paper 3 assesses the science process skills you use in the laboratory, so marks reward how you handle an investigation rather than recall of facts.

• Making a hypothesis, writing a testable statement that links the manipulated variable to the responding variable.
• Controlling variables, identifying what must be kept constant and stating how each one is fixed.
• Measuring and using numbers, reading instruments to the correct precision and recording units.
• Interpreting data, reading a table or graph and describing the trend it shows.
• Making inferences, giving a reasoned explanation for a result, based on the data.
• Communicating, tabulating readings and plotting graphs clearly, with labelled headings and axes.

Worked Paper 3-style examples

These original examples show the standard of answer expected for common Paper 3 tasks.

Task 1 (hypothesis). An investigation studies how temperature affects the rate at which amylase digests starch. Write a hypothesis.

Model answer. As the temperature increases up to the optimum, the rate of starch digestion increases, because the enzyme and substrate molecules collide more often; above the optimum the rate falls as the enzyme denatures.

Task 2 (variables). State the manipulated, responding and one controlled variable for that investigation. Model answer. Manipulated: the temperature of the mixture (°C).

Responding: the time for the starch to be fully digested (s), tested with iodine solution. Controlled: the concentration and volume of amylase and starch, kept the same in every test.

Task 3 (tabulation and graph). Readings of digestion time are taken at five temperatures. Describe how to present them.

Model answer. Record the results in a table with column headings and units, such as 'Temperature (°C)' and 'Time (s)'. Then plot a graph of time (s) against temperature (°C), choose an even scale, and draw a smooth curve of best fit.

Task 4 (conclusion and inference). The digestion time is shortest at 37 °C and longer at 20 °C and 60 °C. Write a conclusion.

Model answer. The rate of starch digestion is highest at about 37 °C, the optimum temperature of amylase; it is slower at 20 °C because the molecules have less kinetic energy, and slower at 60 °C because the enzyme has begun to denature. This supports the hypothesis.

Managing the planning and answering time

The practical test allows 5 minutes planning before 40 minutes answering, so use each phase for a different job.

During the planning time, read the whole question, underline the variables and the quantity to be measured, and sketch the outline of any table you will need. During the answering time, write the method or fill in the table first, then plot any graph carefully, and leave a few minutes at the end to check units, headings and your conclusion against the data.

Common mistakes

Source:SRC-DSKP-EN

Frequently asked questions