What is a Lab Report?
A lab report is a record detailing how a scientific experiment was conducted as well as what its purpose, findings, and outcomes were.
Lab work is an essential aspect of science education; experimentation along with a meticulous record of the procedure and results are key aspects of the scientific method. Lab reports are, therefore, important logs that should be maintained by anyone—student or otherwise—who works in a laboratory.
The lab report is a succinct document that informs the reader about the hypothesis and/or theories that are guiding the experiment, the precise method and materials used, the data collected, and the conclusion that the experimenter has arrived at. Anyone reading the lab report, with sufficient training, ought to be able to replicate the experiment and verify the findings on their own.
All lab reports, regardless of subject or topic, can be broken down into various elements. Whilst most of these elements are present consistently and the final structure of most lab reports will appear to be the same, variations are likely to exist based on the preferences and requirements of professors and/or universities.
Elements of a Lab Report
1. Title:
The title briefly and succinctly captures the description and/or purpose of the experiment the lab report is documenting. It is densely informative and to the point.
Some universities or professors may require an entire title page; in such cases, the page will need to include a range of details besides the title of the experiment, such as the name(s) of the author(s), the name of the instructor as well as the date and place the experiment was conducted.
2. Abstract:
The abstract is a condensed outline of the lab report; a strict word limit ranging from 100 to 300 words is usually imposed. It summarizes the purpose, findings, and conclusions arrived at. It may or may not include a reference to the theory driving the experiment. While placed in the beginning, the abstract is the last section of the lab report to be drafted.
Abstracts are often only required at the undergraduate level and higher. Most lab reports submitted in high school do not need to include one.
3. Introduction:
The introduction lays out the background and purpose of the experiment. The topic of the experiment is delved into, and it is often in this section that the brief hypothesis (contained within a single sentence) is stated. However, depending upon the format used, the hypothesis may be presented as a section of its own.
Besides the hypothesis, the author may choose to include the theoretical context of the experiment as well as reference previously conducted relevant research and experimentation.
4. Materials and Methods:
This is the instructional element of the lab report. Here, the author lists all the equipment they used to conduct the experiment, any specific conditional requirements as well as the steps that make up the procedure. This section should be detailed so that a reader ought to be able to follow it and replicate the experiment.
Depending on the format, this element may be divided into two separate sections—one to list the materials and equipment needed and one to outline the process.
5. Data:
The data uncovered while conducting the experiment is recorded in this section. Its presentation varies depending on the nature of the data; however, numerical data is often presented in a tabular form for ease of comprehension.
It is important to note the data as is in this section, without attempting to interpret or analyze it in any form. Any processing or interpretation it has to go through will be done in subsequent sections.
6. Results:
If the Data section of the lab report took a tabular form, the information is reiterated as text in this section.
However, it is also here that any further processing, such as calculations or statistical analyses, of the raw data recorded in the previous section is done. The end results can be presented as tables and/or graphs.
7. Discussion and Analysis:
The results and findings of the experiment are analyzed and interpreted in this section. It is the most subjective section of the lab report—the experimenter’s expectations are compared with the actual findings. Whether the hypothesis put forth before the experiment was conducted is still valid or not is stated here, and any possible bias or error is also acknowledged and discussed. Suggestions for further studies and/or research may also be made.
8. Conclusion:
In some formats, this section may be folded in with the Discussion and Analysis. When present, the final findings of the experiment are summarized in the Conclusion.
9. References:
Any previous research that the author/experimenter may have drawn up or referenced is listed here. This is usually an optional section and, in general, is not required in high school lab reports. In other formats, a more extended and comprehensive reference section may be needed, bringing it closer to an index or appendix.
Basic Outline of a Lab Report
- Title
- Briefly describe the experiment.
- Abstract
- Summarize the experiment’s purpose and findings.
- Introduction
- Introduce the topic.
- Describe the experiment’s objective.
- State the hypothesis.
- Present experiment’s theoretical base.
- Reference findings of previous research.
- Materials/Equipment
- List the materials required to conduct the experiment.
- Method/Procedure
- List the steps needed to replicate the procedure.
- Data
- Record the raw data collected during the experiment.
- Results
- Process the data collected.
- Discussion and Analysis
- Discuss the findings.
- Compare the actual results with those expected before conducting the experiment.
- Clarify whether the hypothesis remains valid.
- Discuss possible bias or error.
- Suggest improvements or directions for further study and research in the area.
- Conclusion
- Briefly state the findings.
Example of a Lab Report
The following is a breakdown of an example lab report of diffusion and osmosis.
Title
In this title, the author has chosen to highlight the concepts being studied.
Diffusion and Osmosis Lab
Abstract
Here, a snapshot of the experiment is provided as its purpose and findings are briefly summarized.
The Diffusion and Osmosis Lab determines the molarities of various sucrose solutions based on change in mass. Using table sugar in different amounts of molar concentration 0.0M, 0.2M, 0.4M, 0.6M, 0.8M and 1.0M. The molarity of the sucrose solution in the dialysis tubing determines the amount of water that either moves into the bag or out the bag, which also means its mass changed. The more concentrated the sucrose solution, the more water it caused to move into the bag.
Introduction
The various theoretical concepts that are needed to contextualize the experiment are introduced.
A cell is the basic unit of life, essential to maintaining the physiology of the larger organism. In animals, certain organelles metabolize food into energy and then use the energy for repair, growth, and reproduction. Similarly, chloroplasts in plant cells transform sunlight into energy, a process known as photosynthesis.
Materials move into and out of cells through either passive transport or active transport. Passive transport includes diffusion and osmosis. Molecules tend to move from more crowded to less crowded regions in order to achieve a balance or to reach homeostasis. The cell membrane is selectively permeable which allows the movement of substances, especially oxygen, water, food molecules, carbon dioxide, and waste products into or out of the cell without the use of energy. Movement occurs when there are unequal concentrations of a substance inside and outside the cell.
Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration. Osmosis is the diffusion of water through a membrane. (Westbroek, 2000). Water moves readily across cell membranes through specific protein-lined channels. Whether there is net movement of water into or out of the cell and which direction it moves in depends on whether the cell’s environment is isotonic, hypotonic, or hypertonic. When two environments are isotonic, the total molar concentration of dissolved solutes is the same in both of them. In a hypotonic solution, the total molar concentration of all dissolved solute particles is less than that of another solution or less than that of a cell. In a hypertonic solution, the total molar concentration of all dissolved solute particles is greater than that of another solution or greater than the concentration in a cell.
The introduction section ends with a clear statement of the hypothesis.
The hypothesis for this experiment is “if the mass of the dialysis bags with the sucrose fluids inside changes, it would mean that water either moved into the bag or out the bag and therefore diffusion and osmosis were involved”.
Materials
The equipment needed to complete the experiment is listed.
The materials to complete this experiment are six presoaked dialysis tubing bags, distilled water, sucrose solutions in different moles—0.0M, 0.2M, 0.4M, 0.6M, 0.8M, and 1.0M with each solution in a different color (Blue, Orange, Brown, Green, Red, and Yellow), six 250mL beakers, paper towels, and syringes (without needle).
Method
The steps to complete the experiment are described.
150 mL of distilled water was poured into each beaker.
One side of the dialysis tubing bags were tied off to pour 15 mL of each color of the sucrose solution into the bag using the syringe.
Afterwards, the other side of the bags was also tied off.
The bags were dried with paper towels, and each bag was measured with the electrical scale to record mass.
After measuring, each bag was submerged into the beakers making sure that the distilled water covers the bag for 30 minutes.
After 30 minutes, the bags were removed from the beakers, dried, and measured once again to record if there was a change in mass.
Data
| Sucrose Solution | Initial Mass (in g) | Final Mass (in g) |
| Blue | 17.29 g | 24.08 g |
| Orange | 16.45 g | 21.09 g |
| Brown | 14.98 g | 13.02 g |
| Green | 15.37 g | 17.14 g |
| Red | 16.02 g | 19.20 g |
| Yellow | 16.50 g | 19.57 g |
Results
Here, the information collected in the tables is presented in text form. Further, tables have also been drawn to process the data—calculating the difference in mass before and after the 30 minutes as well as the individual and class average percent changes.
According to the table, the Blue sucrose solution’s initial mass was 17.29g; after the experiment, its final mass changed to 24.08g, having a change in mass of 6.79g, a percent change in mass of 39.27%, and a class average percent change in mass of 49.45%. The Orange sucrose solution’s initial mass was 16.45g; after the experiment, its final mass changed to 21.09g, having a change in mass of 4.64g, a percent change in mass of 28.20%, and a class average percent change in mass of 35.60%. The Brown sucrose solution’s initial mass was 14.98g; after the experiment, its final mass changed to 13.02g, having a change in mass of -1.96g, a percent change in mass of -13.10%, and a class average percent change in mass of -4.91%. The Green sucrose solution’s initial mass was 15.37g; after the experiment, its final mass changed to 17.14g, having a change in mass of 1.77g, a percent change in mass of 11.57%, and a class average percent change in mass of 12.31%. The Red sucrose solution’s initial mass was 16.02g; after the experiment, its final mass changed to 19.20g, having a change in mass of 3.18g, a percent change in mass of 19.85%, and a class average percent change in mass of 18.12%. Finally, the Yellow sucrose solution’s initial mass was 16.50g; after the experiment, its final mass changed to 19.57g, having a change in mass of 3.07g, a percent change in mass of 18.60%, and a class average percent change in mass of 46.46%.
| Sucrose Solution | Change in mass (in g) | Your % change in mass | Class average % change in mass |
| Blue | 6.79 g | 39.27% | 49.45% |
| Orange | 4.64 g | 28.20% | 35.60% |
| Brown | -1.96 g | -13.10% | -4.91% |
| Green | 1.77 g | 11.51% | 12.31% |
| Red | 3.18 g | 19.85% | 18.12% |
| Yellow | 3.07 g | 18.60% | 46.46% |
Discussion
The findings of the experiment are briefly stated and further analyzed.
Using the evidence registered in the Results, it was proven that the masses of the sucrose solutions inside the dialysis bags changed. The change in the mass proves that water either moved into the bag or out the bag. It was also proved that diffusion and osmosis were involved in the experiment. Also, the results let us determine the molarity of each sucrose solution.
The bag with the most change in mass was the one with the Blue sucrose solution. It had a change in mass of 49.45%; this means that it had a high concentration of the sucrose solution, which made a large amount of water—6.79g of water—go into the bag and therefore its molarity has to be the highest, 1.0M to be specific. The Yellow sucrose solution, with the next highest change of mass of 46.46%, was the solution with the next highest concentration of sucrose that made water go into the bag; therefore, its molarity is 0.8M. The Orange sucrose solution had a change in mass of 35.60% and was the solution with the third highest concentration of sucrose that made water move into the bag; this resulted in the third highest change in mass, letting us know that the molarity is 0.6M. The Red sucrose solution had a change in mass of 18.12%, gaining 3.18g more mass because of the water that moved into the bag; it had the fourth highest concentration of sucrose solution, which means its molarity has to be 0.4M.
The solution that had a lesser change in mass of 12.31% than the first four was the Green one. The bag got more water in it because of its lower sucrose concentration. However, it still had a greater sucrose concentration than distilled water so just 1.77g of water got into the bag. This means that the Green solution had a molarity of 0.2M.
The Brown sucrose solution was the only one that had a negative change in mass of -4.91% because it lost 1.96g of its initial mass; this means that water moved out of the bag instead of going in. It also means that the molarity of the brown solution was 0.0M. Actually, with a molarity of 0.0M and distilled water both inside and outside the bag, water was supposed to move out from inside the bag. This would retain the original mass of both the bag and the distilled water, leading to an isotonic solution; however, some sources of error might change the results in a negative way.
Possible experimental errors and their sources are laid out.
Some sources of error could have been the variations in tube sixpence and masses. This variation gives different mass results that could affect the mass in the bag, so we could not have known the exact mass that moved either in or out the bag.
Also, if the bags were not dried well, the water remaining in the bag would change the mass of the bag and the sucrose solution.
Another source of error could be that the sucrose solutions were all mixed together. This could make the solution change its molarity.
Conclusion
The findings of the experiment and their implication is briefly summarized.
The experiment helped us understand the importance of Diffusion and Osmosis. Sucrose solutions with higher concentration inside the bag than outside it got water into the bag. Solutions Blue, Orange, Green, Red, and Yellow had hypertonic solutions in the experiment. This means that water traveled into those solutions. The Brown solution did not get water into the bag because the sucrose concentration inside the bag wasn’t higher than that outside it.
