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Tuesday, December 5, 2023

What is a laboratory report and how is it written?

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A laboratory report , sometimes also called an experiment report , consists of a written document that presents, in a systematic and organized way, the results of a scientific experiment together with the experimental data, the most relevant calculations, the analysis of the results and the main conclusions .

 This document must be able to transmit, in a clear and concise way, what was done in the experiment, what was learned thanks to it and what the results obtained mean.

In teaching laboratory courses, the laboratory report represents the document that the student delivers to the professor or instructor as proof that he carried out the assigned experiment correctly and that the results were as expected. Otherwise, the report also serves as a tool to analyze and justify any difference between the expected results and those obtained in practice, thus helping to develop the critical and analytical thinking necessary to carry out scientific research.

In view of the above, the laboratory report almost always represents a considerable portion of the course grade , so it is advisable to prepare it with the greatest possible care and dedication. Here is a detailed explanation of how to make it.

How to write a lab report

There are a number of general characteristic aspects for the preparation of experiment or laboratory reports. These guidelines include details related to:

  • The way to present the report.
  • The language and style of writing to be used.
  • The general outline or the parts into which the report should be divided.
  • The particular way to cite the work of other authors.
  • The way of presenting the references.
  • Other details related to the format, such as font size, margins, etc.

Despite the fact that there are style guides that standardize most of these elements in a laboratory report (such as the APA style manual, to name a very popular one), each teacher or instructor is free to choose the one they deem most convenient. to assess their students. For this reason, it is important to remember that any recommendations presented here should always be considered secondary to the specific instructions given by the course instructor.

How to submit the laboratory report

This is the first important factor that defines how the report will be worked on. Many professors of laboratory courses ask their students to prepare the laboratory report by hand in the same notebook in which they write down the data and comments during the execution of the practice or experiment.

In other cases, they allow you to deliver a separate report, either handwritten or printed, and even in some cases, in digital format as a PDF document (or both). The main difference between one case or the other is that, in the reports presented in the laboratory notebook, it is generally not required to include a cover sheet or follow a format, while in the other cases it is usually required.

Language and writing style

What practically everyone agrees on is regarding the writing style and the preferred type of language used in preparing a report. Whenever a report is written, care should be taken to observe the following guidelines:

  • The language must be impersonal. The use of the first person is avoided whenever possible, so expressions such as “ I mixed reagent A with B…” or “When I turned on the UV lamp I observed that…” should be avoided. Only when strictly necessary is it acceptable to use the first person plural. An acceptable example would be “Human beings evolved from…”. Note that, in this case, the “we” refers to us as a human species and not to us as individuals.
  • The use of the reflexive form is preferred instead of the active voice with the subject in the first person. For example , when describing the experimental procedure, one always speaks in terms of “This was done…”, “That was mixed…”, such a thing was observed…”, etc., instead of “I did this…”, etc.
  • The language should be formal, as concise and precise as possible, avoiding the unnecessary use of fancy words or hyperbole (exaggerations).
  • Any description must be made as objectively as possible.
  • Care must be taken to make good use of punctuation marks, take maximum care with spelling and follow all the grammatical rules of the language.

A report is an academic document, so any use of vulgar or colloquial language is completely unacceptable.

Parts of a laboratory report

All the sections that can be included in a laboratory report are now described in a general way. Once again, it is important to remember that each teacher will require from their students the format that they consider most appropriate, so some sections mentioned here may not be relevant or necessary in all cases. However, there is a set of central sections that every laboratory report must have, yes or yes. These sections are highlighted with the word (essential) next to their heading, while the others are understood to be optional.

A laboratory report can be made up of the following parts and/or sections:

  1. Front page
  2. Title (essential)
  3. Summary
  4. Introduction
  5. Materials (essential)
  6. Methods (essential)
  7. Data tables and observations (essential)
  8. calculations
  9. Results (essential)
  10. Discussion or analysis of results (essential)
  11. Conclusions (essential)
  12. Figures and graphs
  13. References (essential)

Front page

Lab reports that are issued separately almost always include a cover page. This consists of an individual sheet with the following information:

  • The title of the experiment (will be described in the next section).
  • The name of the author(s) . It is customary to write the first surname first and then the first name, along with the initials of the second surname (eg Parada P., Israel), although this is entirely up to the teacher.
  • The name of the course instructor.
  • The name of the subject or course.
  • The place where the experiment was carried out.
  • The date. This can be when the experiment was carried out or the date the report was delivered.

Title (essential)

The title is indicates what the experiment is about clearly and with as few words as possible. A good title expresses the main objective of the experiment clearly and concisely.


Some instructors require writing a summary that consists of a statement of about 100 words, in which the objectives are very briefly presented, the most relevant results of the practice along with the most important conclusions.


Information about the background of the experiment and the theoretical foundations of the techniques used can be included in this section. The objectives of the experiment, its importance, as well as its hypothesis should also be included in this section.

Materials (essential)

Here are listed all the materials that were used to carry out the experiment. This section is almost always divided into two subsections:

  • One for laboratory materials and equipment.
  • Another for chemical reagents.

The first list includes any glassware (such as flasks, beakers, Petri dishes, wells, etc.), measuring instruments (such as scales, stopwatches, thermometers, pH-meters, etc.) and any other laboratory apparatus used during the experiment (this could include ovens, thermostated baths, autoclaves, etc.). It is recommended to include, as a minimum, information about the manufacturer (brand) and the model of the instruments used, as well as the appreciation and ranges of all measuring instruments.

In the reagents section, all reagents, solvents, culture media or any other chemical or biological substance used are mentioned in a list, also including, at a minimum, the manufacturer’s information (Merk, Sigma-Aldrich, etc.) and its minimal purity. All this information is found on the reagent label. If previously prepared solutions were used, their concentration and any other relevant data must be reported.

Methods (essential)

In the Methods section it is explained clearly and precisely what was done during the experiment, step by step, without including any steps that were in the laboratory guide that have not been carried out in practice.

Data tables and observations (essential)

In this section, all the data obtained during the development of the experiment are included in an orderly manner, preferably in tables, together with any important observations that have been noted.


If the experiment is not quantitative in nature, this section is usually omitted.

The idea of ​​the calculations section is to present a sample of the calculations carried out from the experimental data to obtain the results of the experiment.

Also included here is a sample calculation of experimental errors and confidence intervals, if these are needed.

Results (essential)

When presented separately, all results obtained after carrying out the calculations or taking experimental observations into account are included here. However, in most cases, this section is merged with the analysis and discussion section.

Discussion or analysis of results (essential)

This is perhaps one of the most important sections of the report, since in it the student must use all his knowledge to justify why such or such results were obtained. It corresponds to a purely argumentative section in which the student tries to convince the addressee (that is, the professor or instructor) of the reliability of his results and the irrefutable nature of his conclusions. He will also have to analyze the main sources of error and justify which are the most important sources of uncertainty in the experimental measurements.

Finally, this section also provides an excellent opportunity to justify getting unexpected or erroneous results. A good argument could save a bad qualification due to a bad experimental procedure.

Conclusions (essential)

Here we present the most important conclusions derived from the results and their discussion, without justifying them (that is what the Discussion section is for). The conclusions may or may not be written in the form of a list and you should not forget to write them in relation to the initial hypothesis.

Figures and graphs

The figures and graphs section is optional and many times unnecessary. It consists of a separate section in which all the figures and graphs of the report are presented, duly labeled and numbered, so that the reader can find them all in the same place. However, in most cases (especially in reports in print or in digital format) any graph or figure is included in the relevant section, making this section unnecessary.

References (essential)

All the sources that were consulted for the preparation of the report must be included, including laboratory guides, scientific texts, scientific articles and any electronic document consulted on the Internet. Only those works cited throughout the text of the report, whether in the background, methods, calculations, or discussion sections, should be included in the reference list.

Citations, reference format and other aspects of the report

The rest of the aspects related to the preparation of the laboratory or experiment report usually vary depending on the context of the course. Thus, for example, if the laboratory course is part of the curriculum of a career related to the medical sciences, it is likely that it will be requested to cite, reference and format the report indicated by styles such as that of the AMA (American Medical Association ) . . In chemistry, the ACS (American Chemical Society) style is usually used and in many other cases the use of the APA (American Psychological Association) style is recommended. It is the responsibility of each student to consult with their instructor which style they should use.

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