Below is a sample lab report assignment from a UW-Madison bacteriology course.
We will be using a format for the lab reports which is similar (but modified) to formats for scientific papers. That is, you must include an abstract, introduction, materials and methods section, results section, discussion, and literature citations. Your grade on the reports will depend on completeness, scientific accuracy and insight, organization, and writing skills. We will discuss this more in lab. We expect lab reports to be prepared using modern word-processing programs.
The format is as follows point totals for each section are for a 100 point report. For partial or 150 point reports they will be adjusted as needed.
1. Abstract of experiment. (10 points)
This is a summary of the basic content of the experiment. It should state the purpose of the experiment, mention the techniques used, report results obtained, and give conclusions. The point of the abstract is to give a concise summary of the whole report. The most common mistake that students make is not including summary data. Example:
Chromosomal DNA was successfully isolated from Bacillus subtilis strain 151 using a modification of the Marmur technique. Spectrophotometric analysis revealed some contamination with protein, but little RNA contamination. The pure DNA had a concentration of 1.05 mg/ml with a 10.3 mg total yield. The DNA was sterile, as judged by streaking onto penassay agar.
2. Introduction. (20 points)
An introduction gives focus to the report similar to the "Purpose" written in the lab notebook, but also should put the experiment into context and provide the reader with information necessary to understand the scientific basis of the experiment and the techniques used. In most cases, you should include background information on the organisms used and explain the theory behind the techniques. Much of the introductory material should be referenced and references have been put on reserve for you at Steenbock Library. You are encouraged to also search the library for other relevant references.
3. Materials and Methods. (30 points)
This is a section which will be a major deviation from scientific papers. Instead of asking you to tediously rewrite all your lab notes into a materials and methods format, we instead want you to include your lab notes in lieu of materials and methods. The lab notes should be complete, including all raw data, observations, calculations and appropriate graphs.
We do not expect (nor do we want) rewritten notes.
4. Results. (15 points)
Separate from the lab notes, include a section containing a summary of the final data, presented in a form that is most useful for interpreting the results. A short paragraph should be sufficient, along with any relevant charts and graphs labeled well. Remember to title and provide legends for all graphs and tables. The graphs and tables should be comprehenable independently of their association with the text.
5. Discussion. (25 points)
Discuss the experiment and the results obtained. This does not mean you simply report the results again, but rather interpret and discuss their significance. Results should also be compared with those in the literature, if possible. (Be sure to give proper citations). If problems were encountered during the course of the experiment, how might they be rectified in the future? Are there any other things we could do to make this a better experiment or to more specifically address the initial question posed? Are there any better techniques available that would allow one to more accurately generate data? Is there more than one way to explain the results? Your results may support your initial hypothesis, but there may be more than one conclusion that could be drawn from your results. Lastly, do not spend enormous amounts of time explaining data that cannot be explained!
6. Reference Citations
As required in all scientific literature, statements of fact, not considered "common" knowledge, must be properly referenced. Relevant articles for each of our experiments are on reserve in Steenbock Library.
Give complete citations of all literature cited in the report. What's complete? Here are some examples:
Articles in Journals:
Marmur, J. 1961. A procedure for the isolation of deoxyribonucleic acid from
microorganisms. J. Mol. Biol. 3:208-218.
Articles in Books:
Coakley, W.T., A.J. Bates and D. Lloyd. 1977. Disruption of bacterial cells. p279-341. In A.H.
Rose and D.W. Tempest (ed.), Advances in Microbial Physiology, Vol. 16. Academic Press, London and New York.
Department of Bacteriology
University of Wisconsin-Madison
LeFevre General Lab Notebook “RULES”
1. Each report must written in the same lab notebook. Blue or black ink are the preferred method.
2. Your first and last name, period, instructor name should be written on the cover of the lab notebook.
3. A table of contents will be made on the first page which will include the title of the experiment and the page number on which the experiment begins. (Don’t forget to update your table of contents regularly)!
4. Each page must be numbered.
5. Each experiment must have a descriptive title written on the top line of the beginning page for that report. You might also want to put the date the experiment was performed on this page.
6. Blank data tables may be made using Word or Excel in preparation of the experiment.
7. You may cut and tape the data table onto a page, but the data itself must be written in during the experiment in the classroom.
8. All calculations must be handwritten. Work must be shown for any calculation you perform. No exceptions!
9. No Xerox copies or re-typed copies of any part of the lab handout or another person’s report are acceptable!
10. No additional pages may be attached to the pages bound in the composition notebook.
11. Each student is responsible for his or her own lab notebook. Lab notebooks may not be shared or passed between students.
Please Note: Only lab notebooks that follow the above guidelines will be allowed for use on lab evaluations!
Lab Notebook Expectations
Your lab notebook will soon become your most treasured document in this class. (Well, that and your periodic table)! Although I will assess your lab notebooks from time to time, they are primarily an important learning tool for you. Labs often guide the curriculum in chemistry, so to be successful in this class it is imperative that you understand what is going on at all times during a lab! If you areasked to perform a certain procedural step or calculation and you don’t know why you were asked to do so…ask!
LAB REPORT TEMPLATE
The different sections of a chemistry lab report are listed and described below. The following lab report format should be used with all labs. Parts 1-4 will be your pre-lab portions of the report. You will complete parts I-III before the lab so you can familiarize yourself with the lab and make predictions about the results. There may also be specific prelab questions to answer in the lab hand out. Note you are creating a table to record your results before the lab and will include your data during the lab. Parts IV-V will be answered after the lab is completed.
Lab titles should be brief but descriptive. Don’t call a lab “Lab #7,” for example.
This is a brief description of what you are attempting to do. Put this into your own words, and in complete sentences. You are summarizing, in a sentence or two, why you are doing the lab – what problem are you trying to solve?
This is a brief outline or illustration of what you will be doing in the experiment. Try to summarize the lab handout’s procedure in 5 sentences or less. It is not necessary to include detailed directions with exact amounts of chemicals, etc.
All data should be organized in a neat, orderly form. Be sure to label all data carefully, use correct significant figures and units. Leave yourself some space! Don’t try to cram information in to a tiny table just to get it to fit on one page!
Description of calculation
Show all work. Including molar mass calculations.
Write the correct number of significant figures.
Show unit conversion factors: 1g O2 * 1 mol O2/ 32g
*Important: All lab partners must have their own copy of the data at all times. Do NOT rely on your lab partner writing down the information for you – you need a copy too!
Label all axes with descriptions and units. All graphs should be done using Excel or some similar program. Please ask if you need help with this!
Clearly label each calculation being performed and include units on your answer. Do NOT simply write down the calculation itself or – worse yet – just the answer! Label what the calculation is: (Density of Aluminum = 8.1 grams/ 3.0 mL = 2.7 g/mL, for example). It is only necessary to show one example of each different type of mathematical calculation performed. There is no need to show your work for five identical calculations in your lab write-up. A helpful suggestion – put all of your “repetitive” calculation results into a table. This will make it easier to spots mistakes you might have made or to find a pattern in your data.
Questions for Discussion
Answering your questions will show your understanding of the lab. You will be asked to describe and analyze your experimental results in this section. Your answers should be written in such a way that I am able to tell what the question was without having to look back at the lab handout! The questions for discussion often address the following:
·What was the experiment about? What was the purpose?
·What did I do? And WHY was the procedure set up this way?
·Were there any new experimental techniques I learned in this lab?
·What was (were) the important chemical reaction(s) in this lab?
·What did the calculations show? What equations did you use?
·How did you reach your conclusion? Did you compare your results to any known values?
Make a simple statement or two concerning what you can conclude from your experiment. This should be brief and refer back to the purpose. See the examples below:
A bad conclusion: very general and often signals a student didn’t really learn anything from the experiment or understand why they were doing it in the first place!
“This experiment was fun. I learned how to calculate density and measure volumes and masses.
A better conclusion: this refers back to the purpose of a density experiment where a student was asked to identify a piece of an unknown metal.
“The average density of our assigned metals was 3.1 g/mL. This metal is most likely aluminum, because our textbook says that aluminum should have a density of 2.7 g/mL. None of the other textbook values came as close to our calculated result.”Use a two-column presentation in the Conclusion-Support format.
Restate the objective
2. Evidence from your data/observations to support answer.
3. Elaborate on evidence. Is the actual value different from the theoretical? Why?
Experimental Sources of Error
Often times there will be questions in your “questions for discussion” section that ask you to analyze how different factors could have contributed to error in your results. You should consider how those sources of error affected your results – do they make the values obtained higher or lower than they should be? What was your percent error?
% Error = (Theoretical - Experimental) / (Theoretical) X 100