GCSE Science: How To Design The Perfect Experiment

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Amy studied at the University of Bristol and is our revision blog guru. She only graduated recently so understands the pressures of being a student better than most, and is here to share her wisdom so that you revise effectively, smash your exams, succeed at school and write cracking university and job applications.

While GCSE past papers will be central to your revision strategy and focus, it can be easy to forget that 15% of your final GCSE sciences grades are actually made up of the assessment of practical experiments during the exams.

The nature of the experiments you’ll have to set up, conduct, record and evaluate throughout the year will vary between GCSE Biology, GCSE Chemistry and GCSE Physics; but there are a few things that practicals across all three disciplines require if you’re to get top marks.

1. Plan everything thoroughly  

One of the biggest keys to a great GCSE science experiment is preparation. Going into the investigation, you have to map out everything you can. Ask yourself these questions before you start:

  • What am I trying to find out?
  • Why am I trying to find this out?
  • What results do I expect to see?
  • How will I go about conducting the experiment? What’s my method?
  • What equipment do I need to carry everything out?
  • How will I record my results?
  • How will I analyse and evaluate my results?
2. Identify the variables 

Another big part of planning is ensuring that both the literal and metaphorical scales are balanced for each part of the experiment.

Before you start the experiment, you have to be sure that the conditions and methods of measuring your results are consistent (or as close as you can possibly keep them) across each stage of your experiment, otherwise your results will not be accurate or reliable.

Remember to work out your dependent and independent variables before your start.

Your independent variable is the variable that is changed or controlled, in order to measure the effects on the dependent variable.

As per its name, the ‘dependent’ variable is reliant on the independent variable, and is the thing being measured in your experiment.

For example: If you’re finding out how exercise effects heart rate in humans, your independent variable would be the exercise and the dependent variable would be the heart rate. You can manipulate and change exercise levels in your human subjects and measure how those levels change heart rate.

3. Keep close track of every result

Casual or lackadaisical result recording can undo a whole experiment, no matter how well-prepared it is. Being careful and precise in your measurements is vital, and it’s important that you repeat the experiment as many times as you see fit (within reason).

Crucially, you mustn’t ignore any results that don’t fit your hypothesis. Anomalies are common, which is why we repeat experiments and measurements in the first place. The combination of close observation, thorough recording of results and repetition will ensure you get the best possible quality results, and therefore the best quality of experiment at GCSE.


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4. Record your results clearly 

Just imagine carrying out the perfect experiment, performed entirely to plan, only for it all to come apart because you don’t record your findings properly.

Keep your notes simple and clear, meaning they’re easily readable and can be easily formatted into graphs and tables at the end, so you can revise them easily for your GCSE exam.

5. Present everything clearly and draw conclusions that fit 

When it comes to presenting your findings, what good are a perfect set of results if they’re unreadable to those who have to assess them? The way you display your results will usually take the form of a scatter graph, with a line of best fit acting as the marker of the trends that draw you to your conclusion.

With that; whether your results match your initial hypothesis, are slightly askew from it, or are the total opposite to what you expected, make sure you draw the conclusion that your results give you and not the one you might have expected or wanted.

6. Evaluate the quality of the data and experiment 

It may feel a little counterproductive to point out where there may have been flaws in your experiment, but it’s actually an important part of proceedings. You have to acknowledge the factors that influenced the results (whether they were in your control or not) and point out how you might have done things differently with hindsight.

Ultimately, it’s important to value preparation, precision and fairness when designing and carrying out your experiment. Do all you can to ensure you have the highest possible quality of results, and that you present them in a way that’s clear and detailed, to give you the best chance of GCSE science success.

Good luck!

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