Science: Lab report

The title should be concise and needs to describe the purpose of the experiment, in a single, precise sentence.

For example: Determining the Period of a Simple Pendulum

Most experiments will involve measuring, observing or developing something. It is clear from the title above that the experiment measured a property called “period”, and the object of interest was a “simple pendulum”.

Sometimes you might be asked to include an abstract in your lab report. However, this won't always be the case, so check your instructions. If you do need to provide one, it should be a brief overview of the entire report, which is therefore the last section to be written. Keep it short: only one paragraph, of about 150 to 300 words.

Your abstract must be clear enough for the reader to understand your experiment without reading the entire report, and is presented as the first section. In general, it summarises each section of your report in one to two sentences, by answering the following questions:

1. What was the aim and research question addressed by the experiment?
2. What method was used to answer the question?
3. What was the main result?
4. What is the significance of this finding?

The introduction is an important part of your lab report. In this section you need to explain the background knowledge related to your topic, including theories and concepts, and any relevant laws, equations or theorems.

The structure often goes from the broad context, offering a review of relevant previous research, and then narrows down to the specific research question you are addressing. It is imperative that you indicate the source of the information you present, by including in-text references to literature, to maintain academic integrity. It is good practice to format them according to the specific referencing style you are using, as soon as you write them in, and ensure you also add them to the list of references. Check the assessment instructions to see if you are expected to use a particular referencing system, or ask a member of the teaching team.

The introduction usually finishes with statements of the aim or purpose of the experiment, and of the hypothesis.

What makes a good hypothesis?

A hypothesis (plural is hypotheses) is a single, clear and concise statement, which:

• Needs to be informed by knowledge from literature
• Is a testable prediction of how the experiment will unfold
• Should only have one dependent and one independent variable (see below)
• Must indicate both variables and the relationship between them
• Can be either supported or disproved by the experimental result

In regards to experimental variables, an appropriately formulated hypothesis should have only one of each of these:

• Dependent variable, is what you measure or observe a variation, and therefore needs to be changeable
• Independent variable, is what you manipulate in order to see if there is an effect or change in the dependent variable

Are these statements well-formulated hypotheses?

For each statement, decide whether it is a well-formulated hypothesis. If not, explain why.

1 The older age group is much more likely than the younger group to drink coffee and eat porridge first thing in the morning.

2 Reading ability in children is related to parental attitude towards education.

3 During the last week of each semester there is an increase in the number of students using the library.

4 It rains more during the Wimbledon tennis tournament than during the Australian Open.

This section offers a detailed account of how you conducted the experiment. It should contain enough guidance for others to replicate the procedure and achieve a similar result. Accordingly, it needs to include relevant information, which depending on your discipline, might include: number of participants; specific tools and/or pieces of equipment used; chemicals/solutions and their concentration. Furthermore, it is preferable to use reputable conventions for indicating numbers, such as the Monash editorial guide, and it’s fundamental to use the correct units of measurement from the International System of Units (SI Units).

This section should also include any changes made to the original protocol which unexpectedly occurred during the experiment. A great way to keep track of these changes is to use a lab notebook to record them, along with any additional useful information that might be important when analysing the results.

Turn your lab protocol into the method section of your lab report

You will generally be provided with a set of instructions, called a lab protocol, to complete your lab work. These instructions often include information such as:

1 how to set up and use the apparatus and equipment

2 a list of materials

3 the steps needed to collect the data

4 any potential experimental difficulties and how to resolve or avoid them.

Below is an example of instructions to carry out a first-year chemistry experiment:

Lab protocol

These instructions, including specific information such as  'use a clean pipette…' or 'remember to take the reading from the centre of the meniscus…', are very helpful for a student who may be performing the technique for the first time. However, they are not relevant information that needs to be included in the lab report.

Moreover, while the instructions are written in the present tense, your methods section should be written using the past tense, as you are reporting something that you’ve done previously.

Lastly, while lab protocols are often written as a step-by-step set of instructions, using bullet points, the methods section of your lab report generally needs to be written as a cohesive paragraph.

Nevertheless, there are ways you can change the language of the instructions to write your method section. Below is an example of how the previous lab instructions were summarised into a paragraph in the methods section of a laboratory report:

How to use the passive voice in lab reports

In the example below, the first person plural is used in the active voice, i.e. "we initiated". While most science units require that you report in the passive voice, some require the active voice. Check your unit information or ask your teacher.

In the results you need to present the data collected during your lab experiment. This section should include:

• a factual summary of the major data trends or patterns. The text should not include any interpretation or explanation of the data, nor does it need to include specific data values. Conversely, the text must include explicit references to the specific table and/or chart where the data is presented.
• the data results, usually presented in tables and/or figures, after any necessary calculations and analysis, including statistics, were performed.

Calculations

When you take your raw data and perform some sort of mathematical operation, it is good practice to show the equations or formulas you used in your analysis, as well as one worked example. Calculations that are very long, or repeated multiple times, are usually included in an appendix (see below).

In some disciplines, if formulae are used, it is common to number them as equations. Check some examples below:

Error and statistical analysis

Error analysis is a type of calculation that indicates the accuracy of your results, usually done by determining the level of uncertainty. The sources of error that you need to consider will vary between experiments and disciplines, but you will usually need to factor in both random and systematic errors.

Any analysis and calculations of the errors or uncertainties in the experiment are included in the results section, unless otherwise specified. In some disciplines the analysis and uncertainty calculations are presented under their own heading. Check the requirements given in your unit information or lab manual, or ask your teacher if you are unsure where to place calculations.

If you carry out statistical analysis you need to indicate the test you performed, and relevant information such as significance and level of probability.

Tables and figures

Most numerical data are presented using tables and/or charts, which are labelled “figures” in a lab report. All of them need to be numbered sequentially and to be explicitly mentioned in the text.

Both tables and/or figures must have a caption, following standard conventions - check the examples below for required information. The positioning of the caption, however, often varies between tables (usually placed above) and figures (usually placed below), although you should check the requirements of the specific referencing system you are using.

Any measurements, either indicated in the text or in a caption, as well as in a column/row of a table or on the axes of a graph, must be accompanied by the respective units associated with it (usually in brackets). However, some measurements such as pH or Absorbance, do not have units, whereas other times a measurement can have a combination of units. For example, in the table below, the units of measurement for the speed 374 would be m/s and the units of measurement for the flow 14 would be m³/s. Always use appropriate conventions for indicating numbers, such as the Monash editorial guide, and the correct SI Units.

Table 1 - Title of the table. Brief description of data, including indication of experimental variables (and their units of measurement) and explanation of any abbreviations or symbols included.

In regards to figures, these can include numerical data, displayed in various types of charts, or images, such as scientific drawings or microscopy images.

If you are using a chart, ensure that you select the right type according to the data you want to visualize. For example, bar charts such as the one below, are great for discrete categories or groups. Other charts, such as scatter plots, are more suitable when the variables are continuous or when you want to show correlations or clusters between your experimental variables. You can also use line charts (suitable for showing change over time) or pie charts (adequate for displaying percentages). To learn more about data visualization, you can access a Sage Research Methods guide, available online from the Monash Library. Note that the formatting of tables and figures varies by citation style.

Figure 1
Title of the chart (In italics)

The figure title should include a brief explanation of the data, of any abbreviations, symbols or colours (which might be shown in the legend), as well as indication of the experimental variables (including their units of measurement). Moreover, it should include statistical information, such as indication of what the error bars represent or if there is significance.

If your experimental result is a scientific drawing or a microscopy image, it should also be presented as a numbered figure, with an appropriate caption below. It is essential that the image includes a scale bar, to give an accurate idea of the actual size of the specimen.

For microscopy images, the caption also needs to include relevant information such as the staining method (if one was used), and the magnification at which the image was captured. If the image is from another source, include a citation, and whether you have modified it, to avoid collusion or plagiarism.

In the discussion you provide an interpretation and an evaluation of your results. Firstly, you need to summarise your key results and explain how they relate to your aim and hypothesis presented in the introduction. You also need to compare and contrast your results with relevant scientific literature, some of which you would have already referred to earlier in the report.

This is a very important section of your report, usually accruing many marks, so ensure you devote a considerable amount of effort, and demonstrate your expertise. Here are some guidelines to assist you writing a comprehensive discussion:

In the conclusion you need to summarise your report, usually in just one paragraph. In this way, it's similar to an abstract, but with more emphasis on the results and discussion. Sometimes this section is not required, so check the instructions for your lab report or clarify the requirement with your teacher.

A conclusion never introduces any new information, results nor ideas. Instead, it provides a brief summary of what has been presented throughout the report. When writing a conclusion you should:

• briefly restate the purpose of the experiment (i.e. the research question you study sought to answer)
• identify the main findings (i.e. the answer to the research question)
• note the main limitations that are relevant to the interpretation of the results
• highlight the significance of the main findings and how they contributed to the broader understanding of the problem.

Conclusion example with feedback

Your lab report must include references to relevant literature, typically in the Introduction and Discussion. These need to be indicated both as “in-text citation” (an abbreviated form, in the specific sentence where you are sharing the information), and as a “full reference” (including all the information regarding that publication, presented as part of a list). The reference list is a separate section that comes after your conclusion and before any appendices (if these are included in the report).

Check your lab manual or unit information to determine which referencing style you are expected to use, and strictly adhere to all the formatting requirements for both in-text and reference list. You can find some of the most commonly used referencing styles, as well as tutorials on citing and referencing, available online from the Monash Library.

References

An appendix (plural = appendices) contains material that is too detailed to include in the main report, such as tables of raw data or detailed calculations.

Each appendix must be:

• given a number (or letter) and title
• referred to by number (or letter) at the relevant point in the text.

Example