Required practicals: how to revise them for the exam

In GCSE Science you carry out a set list of practicals in class. AQA calls them required practicals, Edexcel calls them core practicals and OCR calls them PAGs (practical activity groups). There is no separate practical exam: instead, questions about practical work appear in your written papers. At least 15% of the marks in GCSE science exams are about practical skills.

What you need to know for each practical

For every practical on your course, you should be able to write down:

1. The aim – what you are trying to find out.
2. The equipment – and why each piece is used.
3. The method – step by step, in order.
4. The variables:
   • independent – what you change,
   • dependent – what you measure,
   • control – what you keep the same.
5. Risks and safety – the hazard and how to reduce it.
6. Results – how to record them in a table and plot a graph.
7. Conclusion – what the results show.
8. Errors and improvements – what could go wrong and how to make it better.

Key words you must know

• Accurate: close to the true value.
• Precise: repeat readings are close to each other.
• Repeatable: you get similar results if you do it again.
• Reproducible: someone else gets similar results with different equipment.
• Random error: makes readings scatter; reduce it by repeating and taking a mean.
• Systematic error: shifts all readings the same way, e.g. a scale that does not start at zero.
• Anomaly: a result that does not fit the pattern.

A simple way to revise them

Make one revision card (or one page) per practical with the eight headings above. Then:

• draw the equipment as a labelled diagram,
• cover the page and write the method from memory,
• practise past exam questions on that practical.

Common exam questions

• Name the independent, dependent and control variables.
• Suggest why a result is anomalous.
• Explain how to make the results more accurate.
• Plot a graph and draw a line of best fit.
• Calculate a mean, ignoring anomalies.

In short

Practical skills are tested in the written exams. For each practical, know the aim, method, variables, safety, results and errors, and practise the exam questions that go with it.