Writing Up an Experiment
An experiment should be written up in several sections.
State clearly the aim of the experiment. It should be clear and concise. Don't quote from the teacher – many others will do that. Write a hypothesis so that you can test it and hopefully draw a clear conclusion as to whether or not it is true.
Give some background information, maybe explaining why your experiment is necessary.
List the variables to be measured or calculated, stating whether they are controlled – so that you try to keep them constant throughout eg temperature, independent – one that you can directly change – or dependent, so that depends on or is calculated from values of the independent variables. In a circuit you can change the voltage, then the current changes. The voltage is the independent variable and the current is the dependent variable.
Materials and methods
Give a list of all the equipment used in the experiment and the ranges they measure. Include any chemicals used.
Draw a clear labelled diagram of the experimental arrangement. Describe the method. This should describe how YOU did the experiment. Write how the independent variables were varied, and if necessary how the controlled variables were kept constant. Include a description of how the dependent variables were measured or calculated.
Write how you made sure that data was recorded. Describe the method for data collection, i.e. if you had several trials, if you used controls, methods of measurements, if your calculations are correct... Record also any possible measurement errors/uncertainties.
Record all raw data in tables. The tables should be numbered and have captions in which you briefly describe the contents of the tables and how you recorded the results. Titles, units and the uncertainty should be given in the headings of the tables.
Underneath the table briefly describe the results. Describe identifiable trends and account for anomalous results.
Data Processing and presentation
The data should be processed (calculated) correctly and presented in tables and graphs. If you use graphs, they should have a title in which you describe the contents of the graph. The axes of the graphs have to be labelled with quantities and units and the points have to be plotted correctly. Make sure that you use the correct type of graphs. If both variables are continuous, plot a scattergraph.
Error analysis should be carried out if possible and error bars included in the graph.
Discuss the results you obtained. Does it support your hypothesis or not? Is your hypothesis proved or disproved? Write a conclusion based on your data and the graphs drawn.
Compare your results with literature values if possible.
Evaluate your method. Identify and discuss weaknesses in your method and in the way the data was used.
Identify sources of error – random or systematic, and discuss how they could be reduced.
Suggest practical improvements – not costing too much money and taking up too much time - to the investigation.
Discuss related possible experiments and new questions that could be posed.