Glencora Borradaile

         Associate Professor & College of Engineering Dean's Professor, School of Electrical Engineering and Computer Science, Oregon State University

October 14, 2010

Experiments in teaching: problem-solving sessions

In a more significant experiment than the am-I-ready-for-this quiz, I am rethinking the assignments that accompany my grad algorithms course.  In last year’s class, I had the grad students work in randomly-assigned and rotating (different for each assignment) groups.  I will comment on this in another post.

I’m sticking with the group-based approach – partly for feasibility.  But rather than having standard written submissions and written comments/grades, I am having the students participate in a type of problem-solving session; and idea I stole from Claire Mathieu.

Each group will prepare solutions to some (2) problems ahead of the 2-hour problem-solving session.  Each group (A) will explain the solution to one of their problems X (picked by me) to another group (B) who will then explain the solution to me, with instant feedback/help/cleaning. Group B should leave the session satisfied that they understand the solution to X and will prepare a written solution within 2 days.  The grade of both group A and B will depend on the oral explanation I was given and the written solution to problem X.  Every group will take the role of teacher/student for one problem (that is, group B will then explain the solution to one of their problems, Y, to group A).  The written solutions will be placed into a (private-to-OSU) repository for other groups to see.  For details, see here.

Students are encouraged to repeat this process for other problems that they did not solve or learn; there are as many problems as groups (12) and every student knows who has solved each problem.  I’m hoping this will be a helpful, less lonely, way for them to prepare for the midterm and final (which will determine the bulk of their grade).

I’m hoping that this will help students learn to solve the types of problems they will be asked on the midterm and exam, and (more importantly) that they might face in their research (or in job interviews).  I’m also hoping that it is a more effective use of class time than hearing me lecture for another 2 hours a week. (I have 4 total hours per week of class time).

As before, I will (bravely) ask my students to comment.  I will try and do my best to take the comments into consideration to improve the remaining 5 problem solving sessions.  I have already received one comment that will take effect next session: in the last session, some problems went undiscussed; in future sessions, every problem will be discussed (by some pair of groups) and posted to the repository.  Comments from non-students are always appreciated!

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  1.   Vivek — October 14, 2010 @ 9:29 am    

    Hello Dr. Borradaile,

    This exercise is great. It helps us in learning techniques to solve crucial algorithmic problems. This seemingly daunting task becomes much easier when we work in group with intention of explaining solution to other group. There is one particular thing I felt odd was, the part where we write solution explained to us by other group. Indeed, when somebody finds a solution to a problem, that person feels a sense of ownership to that solution. I feel this feeling could help/motivate us to write a better writeup for the problem.

    But, after-all it is your decision.

    Thanks for giving me this opportunity to write a feedback.

    Best regards,


  2.   victim of master theorem — October 14, 2010 @ 1:51 pm    

    Maybe I’m just weird, but it seemed to me that the anxiety expressed by the class over how this exercise went was way out of proportion to the actual consequences it will have for our grades and our preparedness for the midterm and final exams. You already made clear that it is easy to get a good grade for these homework sessions if you put in the effort, get correct answers, and work as a team (which makes getting correct answers a little easier, right?). And as for test preparedness, its nice that you’ve gone out of your way to give us a chance to prepare ourselves and each other for tests using class time, but the responsibility for being prepared is still ultimately our own. We have a textbook, homework exercises and online resources for that if we feel that the homework sessions alone were not enough.

    In short: I thought the concept/execution of the homework session was fine. If we could keep it from running over class time, so much the better, but otherwise no complaints.

  3.   Shahed — October 14, 2010 @ 10:45 pm    

    I think this is excellent.
    Personally I always feel the best way I can assure that I understood something is only if I can explain/teach that to someone else.

    However, I am worried as in this way I am practicing to solve less number of problems. For example, there were 15 problems on HW1, and as a team we solved two problems and the other team explained one to us. That leaves 12 problems which I had not attempted (except for a few). A regular homework strategy might have forced me to do all the problems and could have been a good preparation for the exams ahead!

  4.   Night Rider — October 15, 2010 @ 4:28 am    

    I’m talking about first 10-15 minutes of each lecturing sessions. I don’t understand why are you voting for each main part of the plan, I’m proposing having some commitment and discuss the result after some weeks (or whole quarter) and just modification of minor details. ’cause If it’s on vote, I prefer not to do group discussion or at least doing it with a group of people that I’m comfortable with, that’s how group work works.

    Anyways, by this procedure, I think students end up memorizing other group problems for exams and just be the master on their assigned problems, in this way, if you give similar questions on exam(s), n-3 students gonna be angry 😀

    I’m also proposing Final exam too be take home like last year…

  5.   Super Algorithm Geek — October 15, 2010 @ 6:46 pm    

    I think your approach is pretty nice, specially during the teaching session. But I also have some criticisms:

    1- In this school the terms are very short, and you have specified a whole class per week to problem solving, do you think you will still have time to cover all materials?

    2-All students in this class are graduate, so they have somehow passed some of these materials in their undergrad, so I think it’s better to just quickly review the basic materials and jump to elaborating higher importance details.

    3- I think basing the grades on oral representation of students in the problem solving session can not be fair, especially since some problems are harder than the others…

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