How to write an assessment report
Learning how to write a good lab report is like learning to ride a bike. Once you’ve figured it out,
you can do it over and over again.
Writing good lab reports is very important in IB as they make out a big part of your final grades
in the science subjects. The key to writing a good lab report is to find out what is asked for and
include all those parts in your report. Here are some steps to follow:
- First you should give the aim of the investigation. It should be clear and concise. If the teacher states the aim you shouldn’t just copy that down, you need to change it to get a full score.
- Second, you need to write the hypothesis and prediction of the investigation. The hypothesis needs to be very clear, giving an exact and complete description of what might happen (and why). The prediction is written like: If …then…
- You can also give a general background to the study if you feel like it’s relevant and necessary.
- Here you should present the different variables. The independent variable is the one that you alter throughout your experiment. For an example, if you investigate the effect of temperature on yeast fermentation, then the different temperatures that you use are the independent variable.
- The dependent variable is the variable that you measure. Using the yeast example, the dependent variable would be the amount of CO2 produced by the yeast (this shows how well the fermentation is going).
- The controlled variables are the ones that you try to keep constant throughout your experiment so that they don’t affect your experiment. If investigating the effect of temperature in yeast fermentation, the controlled variables would be the amount of yeast and water, the time for fermentation, etc.
Materials and methods
- First give a list of all the equipment used in the experiment. Give the size of beakers/measuring cylinders, etc, used, give the names of any chemicals that are used in the experiment.
- You can use a diagram (picture) to show the experimental set up if you find it necessary.
- Now you should describe the method. It should be written in past tense (i.e. not written as a guide on how to carry out the experiment again, but rather, how you did it). The steps in the experiment are either self-evident or explained.
- In this part you should explain the different variables. Write how the independent variable was varied. Using the yeast example, the independent variable can be varied by
placing the fermentation tubes in hot water baths of different temperatures.
- Write how changes of the dependent variable were monitored. You should write how you got your results, e.g. by reading from the scale on the fermentation tube to see how much CO2 that has been produced.
- Write how the controlled variables were controlled. Using the yeast example, you write that you made sure that the amount of yeast used in each fermentation tube was the same (because you used a scale), that you used a watch to make sure that the time that the tubes were allowed to ferment was the same for all tubes.
- Write how you made sure that the sufficient relevant 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, etc.
- Record all your 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 you can briefly describe the results. You can describe the main trends and account for any anomalous result. You don’t have to discuss the significance of the results to the aim of the investigation.
Data Processing and presentation
- The data should be processed (calculated) correctly and presented in tables (as above) and graphs. If you use graphs, they should have a caption in which you describe the contents of the graph. The axes of the graphs have to be labelled with units and the points have to be plotted correctly. Make sure that you use the correct type of graphs. If both variables are continuous, use a point graph . For HL: Error analysis should be carried out if possible (calculate the percentage uncertainty, etc).
- In the conclusion you should discuss the results you obtained in relation with your hypothesis. Write a conclusion based on an interpretation of the gathered results. Compare your results with literature values if possible.
- In the evaluation you should evaluate the method used. Write about the main weakness of the method used and the weakness in the method of manipulation of data. Write about the source of error, but don’t include personal mistakes. Suggest real improvements (that can be carried out in the school lab) to the investigation. Discuss further investigations that are of interest and can be carried out and new questions that could be posed.