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-02/25/07
I feel I have improved a great deal from the first experiment. Why am I still getting an "average" in technique and writeup? How can I get a better grade?
Yes, you HAVE improved! If I asked you to do lab #1 again, you could
probably finish it in record time!
But you are still getting a 12 in technique and an 80 in your lab
write-up.
...What gives?
The grading for this lab is not one I am fond of, but it is the best way to get
"fair" (as in, not TA-biased) grading for the greatest number of students.
This does not take into account the sometimes statistically biased distribution
of students (unusually skilled, or not... majority senior or
sophomore). However, Dr. Mallory will not allow more than approx.
1/3 of the class to receive A-level (A- or A) grades.
TECHNIQUE.
Why 12 points?
++ tech.
-- tech.
OVERALL GRADING.
The 80-point average.
Consistent improvement.
Conciseness.
Yields & Purities.
Grade Range.
EXAMS.
Conclusion.
TECHNIQUE
When I say that the average technique grade is a 12, I DO mean it.
Each student starts with a "12". Points are added or subtracted in the 3 categories (Skill&Understanding, Preparation&Efficiency, Safety... see Grading Rubrics, "Technique"), but nearly all students generally receive 11s, 12s, 13s.
Why is this?
Since I need to circulate around the room, I cannot keep a close eye on everyone. Thus, I do not think it appropriate to have wide spreads on Technique, since most students as a whole do "well" (ergo, "doing well" is "average"), and there are plenty of "good" or "bad" things that I won't happen to catch to penalize you or credit you for them.
Dr. Mallory insists that the average Technique grade be a 12. You are a member of an intelligent, competent, hard-working group of Penn students. Unless you are exhibiting superior lab safety & protocol, extreme mastery of the theory and practice of chemistry, etc., your grade will still lie within the "average" regime.++ tech.
Since how early you finish the experiment and/or get out of lab generally reflects how efficient, prepared & well thought out you are, that is the main positive factor in technique points, as well as a good understanding of procedure and theory.-- tech.
Things like having a flask out of the hood uncorked, not being able to answer a procedural or (easy) conceptual question, not cleaning up the area thoroughly, other unsafe procedures, and getting out of lab late can all impact the technique grade negatively.
Broken glass is only an issue if the action that led to breakage was negligent and/or dangerous (ex: letting a flask boil dry, or putting a hot beaker on a cold surface).
OVERALL GRADING
Grading must combine both objective and subjective elements, and TA grades differently.
Since Dr. mallory insists on a strict 80-ish average on every lab, our grades must reflect this. All labs are given written comments and suggestions, and incorrect answers to quetions are given correct (or *more* correct) answers. Most improvements to your lab write-up grade can be done just by reading these notes.Consistent improvement, lab-by-lab.
Students' lab writeups consistently improve throughout the semester (and those who don't improve fall steadily behind). My standards MUST rise with every lab you turn in due to keeping the "average" at 80, so don't worry, you ARE improving, and I see that! But so is everybody else, and my grades must reflect that. I'm a very strict grader.
Conciseness.
I place high value on the "short, sweet, and to the point" entries (I usually reserve at least 1 point in a category for "conciseness"). That does not mean, for example, that I want you to write a shoddy one-sentence procedure! I mean that I want your writeup section (excluding data & observations, but including prelab, results, conclusions, questions, etc.) to be well-organized, lacking in redundant, vague, or circuitous writing, coherent, and correct.
You've all probably heard of or written a "B.S. paper", where the professor says, write a 4-6 page paper on topic ,... and the majority of submissions are ~4 pages of fluff, filler, and redundancy... and only ~0.5 pages of real and coherent thinking (sometimes not even that much!).
As a first-year student, I too have quite a few classes, with reading, homework, and exams. Just as you would rather not have to write a 20-page lab writeup, I would not like to have to read 12 of them. With all these reports to grade conscientiously, I cannot take hours to pick through your paper, and I refuse to arbitrarily give out a high grade just because you've written a lot, and what I'm looking for is *probably* in there.
Please, make it easy on yourself and me, and take a litttle extra time to plan out what you are going to write, and then write less, but write with quality! Legibility helps, too!
Yields and purities.
Yield grades tend to be based on averages (or, for example, in the case of eugenol, a high yield while still excluding ether, which was visible in your IR printout if present).
I take all average yields, as well as visual & instrumental assesment of yields and purities (so what appears on the label of your vial SHOULD match your vial content, more or less; if you weighed your material in a round bottom but transferred with loss to your vial, you should either note the true amount in your vial, or write both the true and experimentally determined round bottom weight), plus random mel-temp assesment to create a relative scale.
For example, if the yield grade for a given material was out of 4 points, below-average would be 2 pts, above average would be 3 points, and only outstandingly good or poor products would receive 1 (very rare!) or 4 points.Grade range.
Due to the relative grading, your grade is scaled so that there are no perfect (95-100pt) scores, and the grade range is typically mid 70s to mid 80s, with an average of approx. 80 +/- 1.
In the end of grading, if I find that the average of the lab significantly exceeds or is below 80, I will tack on or subtract extra points from a section (usually either the observations/data section, or the Sample section).
Since all students will end up with *good* labs and *not-so-good* labs depending on the week's given workload, other exams, etc, the average really DOES add up to ~80 at the end of the 8 labs!
EXAMS
YES, the biggest boost/detriment to your final grade WILL be the exams. I mean it! As long as you are putting a consistent and conscientious effort into your labs and steadily improving in your lab technique during the semester, you will likely not have any issues. The 80% average imposed on writeups will easily be outweighed by how you do on the exams: all of them!
I have taught students that I was sure would get A's, but their grade was dropped down to a B, just because they did GREAT on the first 2 exams, but bombed the 3rd!
Conversely, I had a student who did poorly on the first exam, but did very well on the second two; combined with really exceptional writeups in the second half of the semester, he managed to bump his final grade up to an A-.
Once more, if you have questions about what including something in your
write-up, I usually put points of critical thought in the
"things to keep in mind for your next write-up"
link, updated when I have time during the weekend, but usually by saturday. I
also check email frequently.
-03/22/07
Regarding Lab #6, I did not submit % yields, but it was not explicitly stated on pg. 59 (it only asked for melting points). Why was I penalized?
Any time that a chemist takes the time to run a reaction with measured amounts of
reagent* and then collect (and recrystallize) product, it is
convention to calculate the gram weight of sample and % yield. This is why
you do Reactant / Product calculations in your pre-lab tables!
Furthermore:
Quoted from the Manual pg 10:
SUBMISSION OF SAMPLES: Each compound that you prepare (or, in certain cases, only a portion of it) is to be turned in to your TA with your completed Lab Report. The sample should be submitted in a stoppered and labeled vial. The label should specify neatly the following information:
Your name:
Compound:
mp/bp
Yield: Xg (%)
Any supplemental data in the form of gas chromatography traces, infrared spectra, etc., should also be submitted with your completed Lab Report.
In closing, for any sample turned in for your lab, % yields should be
calculated by default, as it is part of your grade for the "Sample (yield,
purity, etc.)" section.
*does not include tests for functional groups
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