Skill O-Obtaining Evidence

To get a mark of 2:

• You need to be able to use simple apparatus in your practical work.
• You should be able to work safely, obeying rules on safety procedures in the lab.

To go on and get a mark of 4:

• You need to make some observations that are related to your investigation. (You make 4 or 5 unrepeated readings.)
• You use simple apparatus to make your measurements. (Use of apparatus such as thermometers, digital meters and measuring cylinders is appropriate for this mark.)
• You make a record of the observations or measurements that you have taken.

To improve on this and get a mark of 6?

• You use a wider variety of equipment with confidence to make accurate measurements. (Try to make your measurements as accurate as possible, perhaps using a burette to measure volumes.)
• You need to obtain a suitable range of readings, so that the results can then be used to pick out a trend or relationship. (Try to have regular intervals between readings and a big enough spread, eg. Choose a range of 6-8 temperatures that are approximately 5 degrees apart.)
• To make your results as reliable as possible, you should also try to repeat each set of readings, so that you can see if they are reasonably similar. (If so, you could take averages. If not, you may have to repeat it again to check. This is important for your evaluation later.)
• Record your all results in a clear table, giving headings and including units. (Try to remember to write down all important details, such as quantities and temperatures, because this can often show what you did to make the investigation fair.)

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

• On top of what you need to do for 6 marks, you need to work in a systematic and methodical way.
• You need to demonstrate a high level of care and accuracy when making your observations and measurements. (You will be expected to be able to use equipment that is more sophisticated.)
• You need to give careful consideration to both the range and the number of observations or measurements, explaining your reasons for the choice. (In investigations such as ecological surveys, it is not possible to make observations that show precision and skill; you would be expected to recognise this, and explain the extent to which your observations are reliable. You can compensate by ensuring that you have a statistically significant number of observations.)