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Hints to TAs for grading lab reports

Page history last edited by Kim Moore 9 years, 4 months ago

About the lab report:


Here's what we told the students:

Lab Reports

At the end of the experiment, your team will hand in a complete lab report.  This is your chance to communicate your work in a style similar to what published scientific journals would require (with a little extra info for your TA).  This report must include three components:


  • A Journal: A clear and concise discussion of what you did, how you designed your experiment, and what results you got, written so that an absent student could understand and repeat your experiment.  If you followed false trails that you gave up, you should explain them here with your reasons for giving them up.


  • Data and Interpretation: A presentation of your data in a form that would be easy for an absent student to understand.  Include a discussion of what your data means, what conclusions you’ve drawn from your data, and a persuasive case to convince your reader that your conclusion is valid.  Keep in mind that a record of raw (un-manipulated) data would never be published by a scientific journal--what of the data that you have collected is necessary to make your case?  Is this data sufficient and convincing?


  • Evaluation: After you’ve had a chance to see what data and conclusions other groups have gotten, it’s important to go back and reconsider what you’ve done.  Here is where you discuss how you could improve upon your experiment (design or analysis), in light of what you learned during lab and during the class presentations.  This is also the place to expand upon the interdisciplinary nature of these labs--how are the things you have studied in other science classes connected to what you have done and learned here?  Do you see other possible applications of these research ideas and experimental techniques?


Here is how I present it to my students, if the above language didn't clarify the ideas for them:


The Journal section is the place where you tell the story of the lab.  How did you decide what to do?  What options did you consider?  How did you decide which choice was best?  Why did you reject the other choices?  Where have you taken care to try to reduce your uncertainties?  How will these choices help?  If you followed a path that led to a dead-end, what convinced you to try something new?  What have you learned from this false trail?  The story of the lab should show clear evidence that you have thought carefully about your experimental design/protocol.  A concise method for collecting the data (with which an absent student could easily reproduce your results) is a good way to summarize your process, after you have explained your story.  If your protocol development included theoretical modeling, these models should be described and justified.


The Data and Interpretation/Analysis section is the place where you show the fruits of your labor.  What data did you collect?  What choices did you make in analyzing your data and why did you make these choices?  Did you encounter any outliers or data that you decided not to use?  How do you justify ignoring this data?  How does your analysis of the data support the conclusions that you have made?  Data should be presented in a way that clearly indicates what you did to the raw data in order to produce the information you used to make your decisions about the results.  TAs usually do not want the 'raw' video data (slice and pixel info), and sometimes may not even want the manipulated data (time and position info)—pages and pages of data tables are not the point (and do not appear in professional scientific journal articles)!  What you present in the report as 'data' is whatever information is necessary to support your argument.  When data is presented, this presentation should indicate what the data is (label and units) and how well it is known (uncertainty).  Graphs used to illustrate data should be preceded by a data table (not quite how journals do it, but it helps the TAs know that students are building graphs correctly).  Graphs should be well titled, labeled (in axes, with units), and legends, error bars, and best-fit lines should be included where appropriate (with equation and R^2).  The analysis should indicate what is learned from each graph and how the graph supports the argument.  Any other elements necessary for the analysis and for supporting the conclusions/arguments should be included, such as references to models and foothold principles.


The Evaluation section presents you with a chance to reflect on your own work, especially in comparison with the work of other groups.  What did you do better than others, and why is your method better?  What did other groups do better than you, and why was it better?  How could you improve your experiment (e.g., experimental set-up, data collection, or data analysis)?  This is the chance for you to critique your work and to demonstrate that you are learning/becoming a better scientist (demonstrate reflective thinking).  This is also the place where you should show your interdisciplinary thinking--explicitly connect these experiments to your biology and chemistry knowledge.  Propose future experiments that build off of what you have learned and could explore new ideas (demonstrate prospective thinking).


Note: If they want, students can chunk this information up in different ways (i.e., the report needn't come in these three sections, or even in only three sections).  What matters is that these ideas are all included somewhere and that the report is clear, concise, complete and convincing.  'Doing science' is not a formulaic activity and report writing shouldn't be either.  There is room for creative choice and innovative structure, but the criteria for rational argumentation and justified conclusions must still be met.


General comments about grading:


Your grading pattern is very important.

  1. Set a high standard from the first and clearly explain what you expect and where they fall short.

Our experience shows that students have mostly not had labs like this before and don't know what to do.  If you don't demand real science from them they will interpret the instructions as "just mess around."

  1. Your grading should give the students feedback on what you want them to do.

This is particularly important in the first and second labs where the students are figuring out what is expected.

  1. Don't "ramp up" your grading.  If they improve let them see it in improved grades.

Some TAs have started with critical comments and then, as students met those criticisms, brought in new criticisms to create more improvement.  This can be very frustrating for students and is one reason why your initial lab grading should be severe--to allow room for improvement.

  1. Grades should be given for good thinking and presentation, not answers.   

These labs are supposed to have students exploring topics experimentally where they do not yet know the answers.  For this to work, it is necessary that you reward a well planned and executed attempt even if it turns out not to work for some reason that they could not have foreseen.

  1. It is crucial for this lab that your grades show a significant distribution (standard deviation). 

If you are giving nearly perfect grades to everyone it means your standards aren't high enough!  Expect more!  Part of having a lab of this sophistication and complexity is to allow students with a variety of skills to succeed in the class.  Some students are poor test-takers but excellent experimentalists.  If you don't allow them to stand out in lab, you rob them of the opportunity to do well in the class despite their trouble with exams.  

  1. Let them know what the components of your grading are for.     

Here's a good pattern.

-- Design and thoughtfulness.  (7.5 pts -- for group report)

Did they do a careful and thoughtful job in creating their experiment and was this thought reflected in the journal?

-- Clarity and completeness. (7.5 pts -- for group report)

Did they explain the experiment so that someone else could reproduce it?

-- Persuasiveness.  (7.5 pts -- for group report)

What conclusions did they draw from their data, and were they able to back up these conclusions with their data in a convincing way?

-- Evaluation and Prospection. (7.5 pts -- for group report)

After the group discussions it is useful to give the group 5-10 minutes to write a one-page "How I would do this experiment differently if I had to do it again."  This will encourage them to pay attention and take notes during the discussion and will help them learn to evaluate their work.  They should also critique their choices in experimental design and data collection and analysis and showcase their interdisciplinary thinking.

-- Participation. (3 pts per week  -- for individual)

This is not from the report (and NOT solely for participation in the design and carrying out of the lab) but from participation in the end-of-lab presentations and discussion.  These points are for actively participating in the presentation and delivery  and for asking useful questions or making comments that were valuable to the other teams’ write-ups of their evaluations.


This is the General Grading Rubric the students have seen:

Criterion: Lab Report (as a team)

Points for a 2 week lab

Design and thoughtfulness. Did your team do a careful and thoughtful job in creating your experiment, and was this thought reflected in the journal?


Clarity and completeness. Did your team explain your experiment so that someone could reproduce it?


Persuasiveness. What conclusions did your team draw from your data and were you able to back up these conclusions with this data in a convincing way?


Evaluation. After observing the experiments of other groups, were you able to critique your own lab, propose constructive changes, or explain why your experiment was better than those of your classmates?  (The question you are answering in your evaluation is, “If I got to re-do this experiment next week, how would I do it differently?”)


Criterion: Participation (as an individual)


Contribution to team presentation: Did you participate constructively in your own group's work (protocol development and data collection)?  Did you actively participate in both the preparation of the report/presentation and its delivery?


Contribution of other teams’ presentations: Did you ask useful questions or make comments that were valuable to the other teams’ reports of their evaluations?  Did you participate in both class and small group discussion? 



About constructing rubrics/grading using rubrics:


When I am grading, I make a different rubric for each lab.  Using the general rubric above, I think about what elements students should include in their report for this specific lab that demonstrate the criteria of thoughtfulness, clarity and completeness, persuasiveness, and critical evaluation.  I often emphasize a particular idea/method to the students in the lab (and tell them I will look for it in their lab reports).  I distribute the points for each criterion among these elements and emphasized ideas.  I write out a clear plan and then I grade the reports.  If I encounter strange situations, I make a note to myself of what I have done so that I can be consistent if that situation occurs in another report.  After I have graded the last report, I look over the first report that I graded one more time to make sure that I have not become more/less strict as I have graded the set.  If necessary, I adjust my grading appropriately so that the reports have been treated as equally as possible.  [My advice to you (learned from my own experience): Never grade angry.  If something upsets you, stop grading, take a break, and come back to the task at a later time.  If I become angry while grading, the scores go downhill quickly because I become more critical and less flexible in my understanding.]


As students are learning to write these reports, they often feel overwhelmed.  There are many ways to deal with this.  One thing that I often do is to grade the first report very harshly, using the standards that I will expect of them by the end of the course (i.e., standards I would use for my own work).  I mark their paper to show them what is insufficient or incorrect and explain what they should have done.  I deduct points accordingly.  When I am done, I write the score on the front page and then (since this is only the first lab and they may not have known what to do) I give back half of the points I have taken.  I explain what I did and why I did it to the students when I return their graded work, letting them know that I expect them to work up to my standards on their future reports (when I will not be so forgiving!).


Another thing that I do to help students learn this process is to let them know, for the first few labs, which lab report section/grading criteria I will be grading most critically.  I evaluate the entire report (nothing should be missing), but I pay particular attention to a specific section, bringing all of my expectations to bear (as in the grading of the first report).  This helps students focus their attention on perfecting their work, one section at a time, and then (after the first three or four reports) their work should be at a professional/high standard.  This also helps me to grade the work quickly, as I can skim through the non-emphasized sections, looking only for glaring errors, and then take my time grading the emphasized section, looking for subtle details.  Once students have reached a high standard in their work, the entire report becomes much faster to grade and I can look critically at the whole thing.


It is perfectly okay for TAs to emphasize different lab report sections/criteria/ideas/methods in working with their students.  We don't always have to be perfectly in sync. with each other.  TAs DO have to be consistent within their own course sections and grading.  Also, by the end of the semester, all TAs should have their students working at a high level and producing good reports.  (That way the students will all be at roughly the same level when the end of semester/mid-year shuffle takes place.  Second semester course sections will contain students from a mix of other sections (and a mix of TAs) from first semester.  So that we can start off smoothly in second semester, we all need to have done our jobs well in first semester.)


Example Rubric (Lab 1, Part 2):

All of the above is well and good, but isn't it nice to see something concrete?  Here is a practical application of the above principles.  You don't have to use this rubric, but presented below is the rubric I have used to grade my students' work for Lab 1, Part 2 (wound closure/antibiotics lab).


Note: This is a ONE WEEK lab, so the points are cut in half.  (Each two-week unit is worth 30 points, so a one-week unit is usually worth 15 points.  Thus this week is 15 points, with an additional 3 points for participation (recorded separately in ELMS).)


Design/Thoughtfulness (3.75 pts. total):

  • 1 pt., Explain what you are trying to do with this experiment

  • 1 pt., Explain what is tracked and why for each video

  • 0.75 pts., Explain what is NOT tracked and why for each video

  • 1 pt., Discuss challenges in gathering data


Clarity/Completeness (3.75 pts. total):

  • 1.75 pts., Is method/protocol clearly and sufficiently detailed? (How many things were tracked in each video? What was done with each of these sets of data?)

  • 1.5 pts., Are all included graphs/data tables properly labeled (title, units, uncertainties, best-fit lines, R^2--no error bars needed for this ONE lab)?

  • 0.5 pts., Is the report well-written? (Grammar, spelling, punctuation, fluidity, word-choice, etc.)


Persuasiveness (3.75 pts. total):

  • 1.5 pts., Is the analysis of the collected data sufficient and correct?

  • 0.75 pts., Is the data used for the final argument (decision re: need for antibiotics) presented succinctly and clearly? (Proper s.f., units, reference to data gathered by other group.)

  • 1.5 pts., Is the resolution of the scenario (decision) presented in a convincing, thoughtful fashion?


Evaluation and Prospection (3.75 pts. total):

  • 1 pt., Is the experimental method/protocol critiqued?

  • 1 pt., Is the analysis of data critiqued?

  • 1.75 pts., Are limiting factors discussed? (E.g., reasons why antibiotics may not be needed (flooding, perimeter, etc.) or reasons why antibiotics may be absolutely necessary (immunocompromised patient, infection of the blood stream, specific strands of bacteria, etc.).)


Participation (3 pts. total): (A bit weird for this one, as there is no 'final presentation' by each group....  Base this off of the quality of participation in the class and small group discussions.  Also, don't stress about this too much.  If you are feeling overwhelmed by all the details, it is okay to give the students the benefit of the doubt.)

  • 0.5 pts., Did the student participate constructively in their own group's work (protocol development and data collection)?

  • 0.5 pts., Did the student engage in class discussion? (Interim or Summary)

  • 0.5 pts., Did the student engage in small group discussion? (With companion group)

  • 0.5 pts., Did the student participate constructively in their own group's lab report (writing a section or revising the final product)?

  • 1 pt., For a student who wasn't reminded by the TA to be more engaged in the lab.  (Basically, subtract a point if you had to intervene to prevent them from slacking.)


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