Practical investigations
Read our general notes on Risk Assessment
Writing reports on investigations
We continue to receive numerous requests for guidance as to how to go about writing up investigations. Here we give some general advice. Note that it is up to you to check that your report matches the requirements in your course specification and fits in with any rules about presentation and length.
Look at the marking criteria in your course specification so that you can make sure that your report gives your teacher the evidence needed to give you good credit.
Divide your report into distinct sections to help any assessor to find what they are looking for.
Go for ‘quality’ rather than ‘quantity’.
The title
Choose a title for your report which makes clear what question you are answering in your investigation.
Planning
Begin your report with a clear statement of the nature and aims of your investigation.
Describe the choices you made when choosing the experimental method(s). Your plan must include full details of all chemicals, including quantities of solids and concentrations of solutions. If appropriate, set out all calculations to justify quantities or concentrations used.
Show how the chemical principles you have studied your course underpin the practical techniques you propose to use. Also explain why your particular plan is likely to produce the precise and reliable results desired. You may wish to support some ideas you have mentioned with references to relevant background reading (remember that these need to be acknowledged at the end of your report).
If you had to modify your plan in the light of experience then you should record this, along with the reasons for any changes made. This is probably the place where you should describe any trial experiments you carried out.
Include your risk assessments for any hazards involved, both for chemicals and procedures. There is no point typing out all the recorded hazards for a particular substance. Ensure that the hazards you mention are selective and relevant to the procedures being used.
Procedure
Give a step by step account of the procedures. Illustrate this part of your report with labelled diagrams of the apparatus.
Results
Record all observations and numerical data collected in an appropriate format. It often helps to present measurements and observations in a table. Include full headings and appropriate units in the headings for columns or rows. Record numbers with an appropriate number of significant figures.
You must include all the raw data even if you then go on to calculate average values. It is important to quote values which later turn out to be unreliable or erroneous.
Analysis
Carry out an appropriate analysis of the data collected, using your chemical knowledge of the relevant principles and concepts you have learnt from your A-level course. Remember to include appropriate equations and formulae.
Set out calculations in full, step by step.
Express final answers to an appropriate number of significant figures, and include units and signs if relevant.
If graphs are involved and these are computer-generated, ensure that they are meaningful and clear, and include appropriate labelling of the axes and correct units. For plots which are not straight lines, it might be preferable to get the computer program to plot the points, but for you to draw the ‘curve of best’ fit manually.
Explain clearly how the evidence from the investigation is related to any conclusions made. Refer back to the title and aims of your investigation and show whether or not you have answered the question you set out to address.
Evaluation
There should be three main parts to your evaluation.
(1) Evaluating the reliability of your data
In a quantitative investigation you must assess the experimental uncertainty associated with each type of measurement. Then you must combine the uncertainties to arrive at an overall range of uncertainty for calculated results.
(2) Evaluating the outcomes when compared with expectations
Compare you findings with any predictions you can make, or with data or results obtained from text books, data books or from the web or any other source.
Highlight any unexpected outcomes and discuss how these might have arisen.
(3) Evaluating the design of the investigation
Identify any limitations of the experimental procedure and evidence collected. Make suggestions about how you could improve the investigation if you were to do it again.
Some course specifications require you to try more than one experimental method. If so you should compare them and state which you think is the better.
References
you must acknowledge all secondary sources used during your investigations, whether these are derived from books or the web. One idea is to insert bracketed or superscripted numbers at the appropriate points in the text of your report, and then to produce these as a list in this final section, giving full details of the book or web reference consulted.
Checking
Take care to check your report before handing it in.
If you have used a word-processor to prepare the report, take care with all technical aspects, such as correct use of subscripts and superscripts in equations, and good quality diagrams of apparatus. Always check spelling.
If you use a spreadsheet such as Microsoft Excel to produce graphs, ensure that you have set up the software to produce the right type of presentation for data. Check that graph axes are labelled and that the scales are right.
Check that you have included signs, units and correct symbols.
Right at the end of the job, just look quickly through the pages to make sure that it's all there.
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debby
this page has really helped me write my report although more detail could go in the conlusion and evaluation as to what examinaers specificially want!
11 October 2007
updated: 20 April 2005
