In high school and university, I spent an extensive amount of time writing lab reports, and as a teacher and tutor, I have edited and marked hundreds of student lab reports. In this blog post, I’m going to share what teachers expect to see in formal lab reports and common mistakes that I have observed students make when writing lab reports.
Why do science teachers like to make high school students write lab reports? Lab reports are a great tool for teachers to assess their students’ writing abilities as well as their knowledge of a particular topic being covered. Lab reports require students to analyze gathered data and are, thus, a great tool for assessing a student’s analytical thinking skills and ability to convey information and ideas. Moreover, teachers love various assessment formats apart from tests and presentations. Furthermore, teachers want to prepare their students for science courses in university, where students would be required to write formal lab reports on a weekly basis.
In many genres of writing, the active voice is encouraged over the passive, but this is not the case when writing lab reports. All of the sections of the lab report should be written using passive voice. That means that no personal pronouns are to be used when writing a lab report. So instead of writing “we determined the coefficient of friction to be 0.31,” one would write “the coefficient of friction was determined to be 0.31.” Pronouns such as ‘I’ and ‘we’ should never be used in lab reports. And since lab reports are written after an experiment, the past tense should be used. Unlike other forms of writing, technical writing such as a lab report should never contain slang and colloquial expressions. A lab report is not to be treated like a creative piece of writing. It is not intended to entertain or evoke humour.
Just like a good essay, a good lab report begins with a good title. A lab report title should be descriptive, but not too long. Oftentimes, I see students that haven’t written lab reports before, write something like “Friction lab report” for the title. A much better title would be something like “Determining the coefficient of static friction between a calculator and a textbook.” The title needs to relate to the purpose of the lab.
After a descriptive title, a formal lab report needs to have an introduction. The introduction needs to be in paragraph form (never use point form for a formal lab report). The introduction needs to include the purpose for carrying out the experiment. It also common to include a hypothesis and what was predicted before carrying out the experiment. A crucial component of an introduction is background information. A person that knows very little about the topic of the lab experiment needs to be able to understand what the lab is about from the introduction. Oftentimes, the most common mistake that I notice when reading student lab reports is that there isn’t enough background information given. When reading this section of the lab report, a teacher is assessing if the student understands the underlying concepts behind the experiment. Since background information is a major part of the introduction, including diagrams and figures can help convey ideas. A reference should be included for images taken from an external source such as a website.
The materials section comes after the instruction. This is generally the shortest section of the lab report since all that is require is to list the materials that were used. Complete sentences are not required for this section, just a list. Following the materials section is the procedure or methods section. At times, the materials and methods are placed into one section. The methods or procedures section should list in chronological order the steps that were carried during the experiment. A numbered list is often used in this section. Paragraphs are not necessary. Just like other sections of the report, the procedure should be written in passive voice without the use of personal pronouns, such as ‘I’ and ‘we’. Here is an example of one step of a procedure: “1. Each test tube was filled with 100 mL of water.” The procedure needs to be clear; a person that wasn’t there when the experiment was performed should be able to replicate what was done and should be able to get similar results.
The results section comes after the procedure. All gathered data is placed in the results section. The results section can include observation tables and graphs. It should contain raw and processed data. Raw data is the data that was gathered while performing the experiment, and processed data is data that was generated using the raw data such as a percent error. All tables, figures and graphs in the results section should have a descriptive title and should be numbered. This would be an example of a table title: “Table 1. Displacements of a physics cart.” Results from experimental trials should be put in tables. It is often useful to present gathered data graphically. When creating graphs, place the independent variable, such as time, on the horizontal axis, and the dependent variable, such as displacement, on the vertical axis. Axes should be labeled and should include the units for each variable. A line or curve of best fit also needs to be drawn or generated used software, such as excel. The line or curve of best fit shows the trend of the data. The biggest mistake students make in the results section is to discuss the results. The results section is only meant to display the data – no analysis or interpretation of the data should be there. Brief calculations can be included in the results section, but long calculations should be placed in the appendix section (placed at the end of the report).
The discussion section is where the data in the results section should be discussed and analyzed. The discussion is usually the longest section of a formal lab report because it is where most of the questions that were raised before and during the experiment should be answered. The discussion section should refer to the tables and graphs in the results section. For instance, one would write “According to table 1,…” or “Referring to figure 2, it can be seen…” If the results that were obtained did not match predictions, explanations should be provided as to why that might have been the case. It is important to address uncertainties and sources of error. For instance, when launching a projectile and measuring its acceleration, oftentimes not taking air resistance into account could be considered a source of error. Another common source of error is measurement error – the equipment that is used to measure has a finite precision. Moreover, measurements made by one person may be different than those made by another. The end of the discussion should include a conclusion unless there is a separate conclusion section. The conclusion should relate back to the purpose of the experiment and the hypothesis. It should answer if the results that were obtained matched what was predicted before carrying out the experiment.
One final note: proper grammar and spelling matters as much when writing a lab report as it does when writing an essay for English. Sometimes students hold the misconception that they don’t have to pay as much attention to how they write when writing a lab report. A lab report might have good ideas, but if they are not conveyed clearly, one is less likely to receive full credit for them when the report is being marked. Grammar and spelling are included in the communication mark for the report. How clearly one writes matters in science as much as it does in other subjects.
