Computer Science 314
This page provides a behind-the-scene look at the process which goes into grading student homeworks for this class. Please take the responsibility which comes with beeing a peer evaluator seriously. There are many benefits of this active learning process, yet the only way it works is if the evaluators are conscientious.
Each student in the class will serve as a peer evaluator once during the semester, become the "expert" for one particular exercise of a homework. As a peer evaluator, you are not required to turn in any part of the homework (although for your own sake, you should take the effort to look at all of the problems and solutions for the missed homework, as that material may reappaer in some form on an exam). Instead, your role as evaluator will be graded by the instrutor, providing you with your score for the given assignment. That score will be based on you meeting the various deadlines outlined in this document, and on the quality of your model solution and assessment of the submitted work. The early work will include preparing and revising a model solution to the problem, and in drafting grading standards that might be used the following week in assigning full or partial credit to solutions submitted by students in the class.
We need five students for each assessment team. Please email your preferences to the instructor as soon as possible. (The instructor will send confirmation upon receipt.)
Please see the assignments page for specific due dates for the homework cycles
The peer assessment cycle for a single homework will encompass a three-week period: the two weeks when students are working on the given assignment and the one week immediately after it has been submitted. Our goal will be to use the first two weeks as effectively as possible so as to minimize the remaining work that must be done in evaluating submitted homeworks (as the peer evaluators return to being "regular" students for the following homework and must make sure to get working on that assignment). Ideally, as soon as students turn in their homeworks, the peer evaluators will walk away with them and can work dilligently in reading, marking, and scoring the submissions. Therefore, we will adhere to the following three-week process:
Homework available to students
Problems divided among individuals on Assessment Team
(one per person)
Work on model solution
First draft of model solution due to instructor
Develop draft for grading rubric for assigning points
Meet/communicate with instructor to discuss model solutions and scoring rubric
Final draft of model solution and grading rubric due to instructor
Students submit homework in class
Peer evaluator walks away with stack of submissions
(next homework available to all students)
Make first pass reading all submissions and adding written comments
(but do NOT yet mark any numeric scores)
Meet/communicate with instructor to discuss rubric and any unusual student solutions
Perform second pass to assign numeric grades to submissions
Graded work returned to instructor, and summary of scores emailed
(keep working, as student, on homework assignment due next Monday)
To ensure the success of the process, it is imperative that the peer evaluators adhere to the following logistical procedures:
Comments and a score should be written legibly, using a pen with any color other than black or blue. (Red pens are available to borrow, upon request.)
Each problem is worth a total of 20 points, and only integral scores should be assigned
The score should be clearly indicated and circled on the top of the first page of the submitted packet (e.g., "17" or "17/20")
When done marking the papers, alphabetize them according to codename and return then to the instructor in the provided folder.
In addition to returning the marked hardcopies of the submitted problems, the peer evaluator should email the instructor a brief summary of all scores for the identified problem. For example, that email may take a form as:
ABC 20 ... XYZ 17
You are to create a model solution for your selected exercise that will eventually be provided to the entire class. A first draft of this solution is due one week before the class's due date, and the final version of the model solution is due on the same day as the class's due date. Please make sure your model solution clearly identifies the homework number and problem letter, but do not identify yourself as the author of the solution. (Although you are welcome to put your name on drafts given to the instructor)
As a student, you may look at a problem, understand it, and write up a perfectly correct solution. It is necessary for a grader to also understand the problem and how to solve it, but even more thought is required, Are other correct answers possible? What are some common mistakes that students might make? Are there good ways to determine whether a student's "strange" answer is correct? These are the types of questions that should be considered in advance in order to make the later grading process more smooth.
Therefore, another goal for the preparation week is to create a formal grading rubric. In essence, the goal is to determine how to apportion the 20 total points among what may be multiple implicit or explicit portions of a complete solution. For example, one might decide how many points to award for a proper treatment of a base case of an induction (and therefore how many points might be deducted for completely omitting discussion of a base case). I generally try to consider the relative challenge that comprise a perfect solution, in determining how many points to reserve for each likely portion. Then I will award partial credit for a subgoal in relative proportion to how close an attempt was to correct.
In being a grader, there are three important goals, fairness, equality and feedback. Fairness means that you have assigned a grade which accurately reflects the quality of each student's solution. That is, it is easy to spot a homework worthy of 20 points or 0 points, but for all those in between you want to think about how much credit different attempts deserve. Equality means that you want to be very consistent in giving equal grades to relatively equal homeworks. Feedback can be one of the most helpful things to a student. If he or she got the answer correct, it may require very little comment. However, when you claim that a student's solution is not perfectly correct, you should make an effort to explain to the student what parts are incorrect and why.
Our method for meeting these goals will be to do the grading using a "two-pass" system. During the first pass, which will ideally take place between classtime on Monday and classtime on Wednesday, the grader should read all of the submitted homeworks. During this pass, write as many notes and comments as you can on the students' homeworks, however no grades should be assigned. Ideally, you might go through each homework, writing down pretty much everything on the student's paper except the grade itself. Comments will help the students understand mistakes, and will also provide a quick way for the grader during the final-pass to remember what was done without having to start from scratch. The worst thing for a grader is to spend a great deal of time trying to understand a student's solution, only to forget about it and have to spend all the time again later. Things as simple as writing down a check-mark on an obviously correct solution, or explaining a mistake on a flawed homework will make it very simple to go back and assign grades later. Additionally, you may want to keep a separate sheet of paper for yourself where you write down a summary of common mistakes and a list of any particularly odd answers which you want to discuss with the instructor.
Between Wednesday and Friday, you should either meet or email the instructor to discuss the various types of mistakes which were seen and to refine the grading rubric if necessary. Obviously, not all of the student's answers will fit exactly to this scale, but by giving yourself enough of a guideline for assigning number grades, you should hopefully be able to make a decision individually for each student during the second pass. You will have until classtime the following Monday to assign final grades, as well as to adjust or add any additional comments that you feel will help individual students understand their mistakes. Remember that you must record all grades both on the front of the student's homework and on a separate summary list that is emailed to the instructor.
Keep in mind that you are a peer evaluator, but you are not a TA for the rest of the class. Although you will become an expert for the particular homework problem, you should in no way discuss any part of the homework with other students who are working on the homework. Any behavior which compromises the integrity of this system will be dealt with severly. Please see the complete policy towards Academic Integrity.
As an evaluator, you also have responsibility in overseeing the academic integrity of the entire class. You do not need to go out of your way to intentionally look for cases of academic violations, but if you clearly observe two or more solutions that are unmistakingly similar, you are to grade them at face value, but send an email to the instructor identifying the potential problem and the codenames involved. The instructor will take over responsibility after that.