Skill P-Planning Experimental Procedures

To get a mark of 2:

• You need to plan a simple safe procedure. (What has to be done, how you are going to do it and how you can carry it out safely.)

To go on and get a mark of 4:

• You need to plan a fair test (Try to show how you are going change only one thing at a time, and say what things you are going to keep the same.)
• You should try to predict what you think will happen when you change this factor.
• You should plan what measurements or observations you are going to take to test your prediction and think about how you are going to record them.
• You need to choose your own suitable apparatus. (Sometimes a diagram will be helpful to show how you are going to use the apparatus.)
• Write clear instructions for your method. (Imagine that you are writing an ‘idiot-proof plan’ that could be followed by anybody!)

To improve on this and get a mark of 6?

• You would need to ‘brainstorm’ a list of the key factors that could possibly affect the outcome of your investigations.
• You need to pick one of these factors and make a prediction about its effect. You should try to justify your prediction using scientific ideas. (Choose a sensible factor, one with ‘in-between values’ so that it is possible to predict a trend. Don’t just copy out information to back up your prediction – you need to use it in a relevant way.)
• You would need to consider other factors that could affect your results and discuss what you need to do to control these so that your experiments are fair. (What amounts would you use each time? Are you measuring in the same way each time? Is room temperature important? Do you need a control experiment for comparison?)
• You should decide on a suitable range of readings to take to get enough results to pick out a reliable pattern. (You need a spread of readings to be able to pick out a pattern. Perhaps you could repeat each set of readings to check reliability?)
• Write a clear, scientific procedure, including the amounts of substances used, details of measurements to be taken, information about any trial runs you have done, what you do to make your measurements accurate and reliable, and don’t forget about safety.

What else would be needed to get a mark of 8?

• On top of what you need to do for 6 marks, you would need to show a good understanding of the science involved and use detail from background reading or research in a relevant way to justify your prediction. (It is not enough to copy out chunks of information – you have to use it!)
• You need to use this theory to plan your strategy so that you have a good chance of getting enough reliable information to get a solution to the investigation. (Perhaps you could explain why the key factors need to be controlled – what effect they might have if they weren’t. You could also explain why you have chosen your range of readings and why you are repeating each set of readings.)
• You need to be clear about what needs to be measured or observed, and you need to select suitable instruments for doing this, using scientific reasons to show why you chose this apparatus.