9 ms·

Jeff Erickson was my algorithms professor in 2012. He exemplifies the articulate, passionate educator that I wish I had for my other CS subjects. I recognize ma

Jeff Erickson was my algorithms professor in 2012. He exemplifies the articulate, passionate educator that I wish I had for my other CS subjects. I recognize many of these notes having read them many times in preparation for quite difficult exams - a fun anecdote shared among people who've taken the class is the 25% credit given on any exam question just for writing "I don't know", effectively a reward for acknowledging your own shortcoming and for saving the TA the time to decipher a bullshit answer. Professor Erickson, if you're reading this, thank you for being the best educator of my college days and for making your beautifully-written notes available to everyone.

gricardo99 8y ago
>25% credit given on any exam question just for writing "I don't know", effectively a reward for acknowledging your own shortcoming and for saving the TA the time to decipher a bullshit answer. That’s brilliant, yet I’ve never heard of it. Should be standard scoring for written exams.
- Vaslo 8y ago
  Random other point of brilliance I've seen: Our Organic Chem teacher (who was loved universally in the Program) had a rule about test corrections. If you wanted a correction to something you believed you should get credit on, he would only offer to regrade your WHOLE test, which meant you could actually get less points on the regrade because it was he and not a TA regrading (could have worked both ways). It really scared off all those one-off "Can I get an extra point here" requests in a 300 person class.
  - edanm 8y ago
    I think that was the way it worked at my university too, at least officially. Unofficially, very few teachers actually graded that way, and when I saw it happen, people complained about it a lot. Then again, the teachers that did it seemed like they were doing it punitively (e.g. subtracting the exact amount of points they were forced to add.)
  - ggggtez 8y ago
    I agree. I've seen this done and it was effective. Combined with requiring the request to be made in person, during office hours, it also got struggling students to actually attend the office hours (which often was otherwise empty, and another waste of the grader's time).
    - skookumchuck 8y ago
      The students I knew who tried to complain their way into a better grade would have been better off if they'd tried to study.
  - jperras 8y ago
    This was the policy for any final exam at my alma mater. You had to be rather certain that you were sufficiently wronged overall, otherwise a few points more on one question could be offset by a large number of negated points from other questions where the professor thought that the TA might have been too generous.
  - danieltillett 8y ago
    When I was a professor this is the way I would regrade too. I would regrade blind to the first mark so I didn’t bias myself. I don’t think I ever had a regrade that changed more than 5% and most were identical. I would also grade all exams the first time blind to who the student was and then regrade a half dozen again to make sure that I hadn’t drifted out of grade over the marking process. I used to play an game with myself (marking is very boring) as to who would get what mark based on my in class knowledge of the student (when you run labs you do get to know the individual students). It was a rare student that got a exam mark more than 10% outside my estimate.
  - SilasX 8y ago
    I’ve never understood why that’s a good policy. You’re (vindictively) punishing the student for pointing out — albeit selectively — where the teacher, supposedly a bedrock of truth on the course material, has falsely labeled your “training data”.
    - nichochar 8y ago
      I think you're running under the assumption that all students making the request are doing it for the right reasons. I could be wrong, but my intuition goes the other way and I'm assuming most students do it to get a better grade, not learn more.
      - SilasX 8y ago
        >I think you're running under the assumption that all students making the request are doing it for the right reasons. No, that's what the "albeit selectively" clause was referring to. >I could be wrong, but my intuition goes the other way and I'm assuming most students do it to get a better grade, not learn more. As in my comment, it doesn't matter. Their job is to be an expert on this material. Failing to correctly label an answer is failing at their job. Punishing someone for pointing out a failure at your job is unprofessional.
      - solveit 8y ago
        Yeah no, you don't get to say students should care more about learning than grades when jobs, opportunities, and scholarships given by the very university that claims learning is more important are riding on grades. It is the professor's responsibility to grade accurately, and honestly if there is so much inconsistency in grading that there's a significant probability that the student will lose marks despite having pointed out a reason they should gain marks, the professor is screwing up very badly[1]. Don't pin that on the student not having noble intentions or whatever. [1]:Or at least that's the case in STEM. My humanities friends tell me that grading is much more subjective there which is a bit disturbing but I'm hardly qualified to make such judgments.
        SilasX 8y ago
  - rdc12 8y ago
    This was a common approach at my Uni. I only once challenged it, but the issue was an entire question wasn't marked at all, so the lecturer didn't remark the rest. One other time, I asked the lecturer (different paper) where I went wrong on a question, and turn's out I was right all along, got that question regraded without the potential downside to a full remark.
- Eridrus 8y ago
  This is functionally equivalent to being given negative marks for getting answers wrong, which I've seen on multiple choice tests.
  - emidln 8y ago
    Only if no partial credit is offered, which is not how his exam[0] reads to me: As usual, answering any (sub)problem with “I don’t know” (and nothing else) is worth 25% partial credit. Yes, even for problem 1. Correct, complete, but suboptimal solutions are always worth more than 25%. A blank answer is not the same as “I don’t know” [0] http://jeffe.cs.illinois.edu/teaching/algorithms/hwex/s18/final2.pdf http://jeffe.cs.illinois.edu/teaching/algorithms/hwex/s18/fi...
    - dunham 8y ago
      I had a math prof who would give negative marks on proofs, preferring you say “I don’t know how to do this step” and finishing the proof over trying to BS the step.
      - thfuran 8y ago
        How do you skip a step in a proof? You just say "assuming I can prove this assertion, this other stuff follows"? That seems to risk accidentally skipping way more steps than you thought you were skipping and quite probably the meat of the proof.
        dragonwriter 8y ago
        > How do you skip a step in a proof? Well, from the math profs I've seen, the usual method is to interpose “it is intuitively obvious” in place of the skipped step(s). The tricky part is having a correct intuition as to what you should be skipping to, sure, but that's the same problem as you have doing a proof (minus actually figuring out the justification) since humans don't generally do proofs by exhaustively listing every possible next step from what is already proven in a BFS until getting the desired result and then pruning all the other paths.
- whymauri 8y ago
  A friend of mine took a game theory class with this system. Partial credit also given for partially correct solution. Completely wrong bullshit answers would lose 10%, or something like that.
  - skookumchuck 8y ago
    Yes, obviously wrong answers (like negative energy) would get negative credit. They'd get >=0 credit if they'd annotate the answer with "I know this is wrong, but I can't find my mistake." Sounds sensible to me.
endlessvoid94 8y ago
I've also taken his class and can attest to his subject matter expertise and excellent teaching style
- steve_musk 8y ago
  Me too. His notes are amazing in my opinion, and I’m really excited to read some of this book that I didn’t cover during my classes. I prepped for all of my interviews by just reviewing these notes, and it seemed to work really well.
alfrapi 8y ago
I think the rule was you had to attempt at least one question (couldn't say "I don't know" for the whole exam). Am I remembering that correctly?
- jefferickson 8y ago
  No, I've had several students answer "I don't know" to every question on the final exam. (About one every two or three years.) Without exception, they got a 25% on the exam and an F in the class. Other theory instructors at Illinois do put limits on their IDK policy, like "at most 10% of the total points", or "for at most one question", or "not in my class". So far I've stuck to my guns.
kaap 8y ago
He was my algorithms professor in ~1999, and he garnered identical praise from our cohort, too. His approach to demystifying recursion is perfect (Chap 1.2): "The Recursion Fairy will solve all the simpler subproblems for you, using Methods That Are None Of Your Business So Butt Out" Thanks for your teaching and for this project, Jeff!
- DonaldPShimoda 8y ago
  I've tried a few approaches to explaining recursion ("just assume that it works", "trust yourself", "turn off your brain" (the latter of which is from Will Byrd)), but I like "Recursion Fairy" an awful lot. Might have to try that next time.
  - emme 8y ago
    We designed a small tool to bring the fairy metaphor even to lower secondary school students. I actually believe it is a very promising approach. "Nothing to fear but fear itself: introducing recursion in lower secondary schools" https://aladdin.di.unimi.it/materiali/pubb/2017_latice.pdf https://aladdin.di.unimi.it/materiali/pubb/2017_latice.pdf
    - ff_ 8y ago
      Super interesting! Do you happen to have an Italian translation/version of the paper?
      - emme 8y ago
        No, I'm sorry... It was thought in Italian... but written only (more or less) in English :-) But the supporting tool is actually in Italian: https://aladdin.di.unimi.it/sw/fatine/ https://aladdin.di.unimi.it/sw/fatine/
      - emme 8y ago
        Just remembered: in fact the work was a master thesis, and the final report is in Italian. http://aladdinsrv.di.unimi.it/archive/pdf/tesi-previtali.pdf http://aladdinsrv.di.unimi.it/archive/pdf/tesi-previtali.pdf Enjoy!
yangdehang 8y ago
making things difficult is easier, the opposite should be promoted.

gricardo99 8y ago

>25% credit given on any exam question just for writing "I don't know", effectively a reward for acknowledging your own shortcoming and for saving the TA the time to decipher a bullshit answer. That’s brilliant, yet I’ve never heard of it. Should be standard scoring for written exams.

Vaslo 8y ago
Random other point of brilliance I've seen: Our Organic Chem teacher (who was loved universally in the Program) had a rule about test corrections. If you wanted a correction to something you believed you should get credit on, he would only offer to regrade your WHOLE test, which meant you could actually get less points on the regrade because it was he and not a TA regrading (could have worked both ways). It really scared off all those one-off "Can I get an extra point here" requests in a 300 person class.
- edanm 8y ago
  I think that was the way it worked at my university too, at least officially. Unofficially, very few teachers actually graded that way, and when I saw it happen, people complained about it a lot. Then again, the teachers that did it seemed like they were doing it punitively (e.g. subtracting the exact amount of points they were forced to add.)
- ggggtez 8y ago
  I agree. I've seen this done and it was effective. Combined with requiring the request to be made in person, during office hours, it also got struggling students to actually attend the office hours (which often was otherwise empty, and another waste of the grader's time).
  - skookumchuck 8y ago
    The students I knew who tried to complain their way into a better grade would have been better off if they'd tried to study.
- jperras 8y ago
  This was the policy for any final exam at my alma mater. You had to be rather certain that you were sufficiently wronged overall, otherwise a few points more on one question could be offset by a large number of negated points from other questions where the professor thought that the TA might have been too generous.
- danieltillett 8y ago
  When I was a professor this is the way I would regrade too. I would regrade blind to the first mark so I didn’t bias myself. I don’t think I ever had a regrade that changed more than 5% and most were identical. I would also grade all exams the first time blind to who the student was and then regrade a half dozen again to make sure that I hadn’t drifted out of grade over the marking process. I used to play an game with myself (marking is very boring) as to who would get what mark based on my in class knowledge of the student (when you run labs you do get to know the individual students). It was a rare student that got a exam mark more than 10% outside my estimate.
- SilasX 8y ago
  I’ve never understood why that’s a good policy. You’re (vindictively) punishing the student for pointing out — albeit selectively — where the teacher, supposedly a bedrock of truth on the course material, has falsely labeled your “training data”.
  - nichochar 8y ago
    I think you're running under the assumption that all students making the request are doing it for the right reasons. I could be wrong, but my intuition goes the other way and I'm assuming most students do it to get a better grade, not learn more.
    - SilasX 8y ago
      >I think you're running under the assumption that all students making the request are doing it for the right reasons. No, that's what the "albeit selectively" clause was referring to. >I could be wrong, but my intuition goes the other way and I'm assuming most students do it to get a better grade, not learn more. As in my comment, it doesn't matter. Their job is to be an expert on this material. Failing to correctly label an answer is failing at their job. Punishing someone for pointing out a failure at your job is unprofessional.
    - solveit 8y ago
      Yeah no, you don't get to say students should care more about learning than grades when jobs, opportunities, and scholarships given by the very university that claims learning is more important are riding on grades. It is the professor's responsibility to grade accurately, and honestly if there is so much inconsistency in grading that there's a significant probability that the student will lose marks despite having pointed out a reason they should gain marks, the professor is screwing up very badly[1]. Don't pin that on the student not having noble intentions or whatever. [1]:Or at least that's the case in STEM. My humanities friends tell me that grading is much more subjective there which is a bit disturbing but I'm hardly qualified to make such judgments.
      - SilasX 8y ago
- rdc12 8y ago
  This was a common approach at my Uni. I only once challenged it, but the issue was an entire question wasn't marked at all, so the lecturer didn't remark the rest. One other time, I asked the lecturer (different paper) where I went wrong on a question, and turn's out I was right all along, got that question regraded without the potential downside to a full remark.
Eridrus 8y ago
This is functionally equivalent to being given negative marks for getting answers wrong, which I've seen on multiple choice tests.
- emidln 8y ago
  Only if no partial credit is offered, which is not how his exam[0] reads to me: As usual, answering any (sub)problem with “I don’t know” (and nothing else) is worth 25% partial credit. Yes, even for problem 1. Correct, complete, but suboptimal solutions are always worth more than 25%. A blank answer is not the same as “I don’t know” [0] http://jeffe.cs.illinois.edu/teaching/algorithms/hwex/s18/final2.pdf http://jeffe.cs.illinois.edu/teaching/algorithms/hwex/s18/fi...
  - dunham 8y ago
    I had a math prof who would give negative marks on proofs, preferring you say “I don’t know how to do this step” and finishing the proof over trying to BS the step.
    - thfuran 8y ago
      How do you skip a step in a proof? You just say "assuming I can prove this assertion, this other stuff follows"? That seems to risk accidentally skipping way more steps than you thought you were skipping and quite probably the meat of the proof.
      - dragonwriter 8y ago
        > How do you skip a step in a proof? Well, from the math profs I've seen, the usual method is to interpose “it is intuitively obvious” in place of the skipped step(s). The tricky part is having a correct intuition as to what you should be skipping to, sure, but that's the same problem as you have doing a proof (minus actually figuring out the justification) since humans don't generally do proofs by exhaustively listing every possible next step from what is already proven in a BFS until getting the desired result and then pruning all the other paths.
whymauri 8y ago
A friend of mine took a game theory class with this system. Partial credit also given for partially correct solution. Completely wrong bullshit answers would lose 10%, or something like that.
- skookumchuck 8y ago
  Yes, obviously wrong answers (like negative energy) would get negative credit. They'd get >=0 credit if they'd annotate the answer with "I know this is wrong, but I can't find my mistake." Sounds sensible to me.

endlessvoid94 8y ago

I've also taken his class and can attest to his subject matter expertise and excellent teaching style

steve_musk 8y ago
Me too. His notes are amazing in my opinion, and I’m really excited to read some of this book that I didn’t cover during my classes. I prepped for all of my interviews by just reviewing these notes, and it seemed to work really well.

alfrapi 8y ago

I think the rule was you had to attempt at least one question (couldn't say "I don't know" for the whole exam). Am I remembering that correctly?

jefferickson 8y ago
No, I've had several students answer "I don't know" to every question on the final exam. (About one every two or three years.) Without exception, they got a 25% on the exam and an F in the class. Other theory instructors at Illinois do put limits on their IDK policy, like "at most 10% of the total points", or "for at most one question", or "not in my class". So far I've stuck to my guns.

kaap 8y ago

He was my algorithms professor in ~1999, and he garnered identical praise from our cohort, too. His approach to demystifying recursion is perfect (Chap 1.2): "The Recursion Fairy will solve all the simpler subproblems for you, using Methods That Are None Of Your Business So Butt Out" Thanks for your teaching and for this project, Jeff!

DonaldPShimoda 8y ago
I've tried a few approaches to explaining recursion ("just assume that it works", "trust yourself", "turn off your brain" (the latter of which is from Will Byrd)), but I like "Recursion Fairy" an awful lot. Might have to try that next time.
- emme 8y ago
  We designed a small tool to bring the fairy metaphor even to lower secondary school students. I actually believe it is a very promising approach. "Nothing to fear but fear itself: introducing recursion in lower secondary schools" https://aladdin.di.unimi.it/materiali/pubb/2017_latice.pdf https://aladdin.di.unimi.it/materiali/pubb/2017_latice.pdf
  - ff_ 8y ago
    Super interesting! Do you happen to have an Italian translation/version of the paper?
    - emme 8y ago
      No, I'm sorry... It was thought in Italian... but written only (more or less) in English :-) But the supporting tool is actually in Italian: https://aladdin.di.unimi.it/sw/fatine/ https://aladdin.di.unimi.it/sw/fatine/
    - emme 8y ago
      Just remembered: in fact the work was a master thesis, and the final report is in Italian. http://aladdinsrv.di.unimi.it/archive/pdf/tesi-previtali.pdf http://aladdinsrv.di.unimi.it/archive/pdf/tesi-previtali.pdf Enjoy!

yangdehang 8y ago

making things difficult is easier, the opposite should be promoted.