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06 July 2015

Mail Time: Is it "fair" to evaluate students on the quality of their homework?

As I was going through emails in preparation for the 2015 open lab (please let me know if you'd like to attend!), I found this:

I saw in your "Less is More" article that homework [was at that time] 25% of the total grade for your classes.  I was considering making homework a much lower percentage but mostly a "good faith effort completion" grade, since I've found it difficult to justify to myself grading students on their knowledge of a material while their still in the process of learning it, rather than an exam where they are reviewing the material.  What are your thoughts on this?

That's an important question for any physics teacher to be able to answer.  Remember that physics teaching is art, not science -- there are few hard truths of physics teaching, only ideas that work or do not work for each of us.  Would pointillism have worked for Picasso?  Could Rodgers and Hammerstein have written about singing cats?  Maybe, maybe not; yet pointillism and Cats! are indisputably successful things that other artists should at least be aware of.  I have my answer to the homework question that indisputably has worked wonders for me and many others.  Some good teachers may disagree with me on principle, or may choose not to use my approach in their teaching environment.  Yet everyone should acknowledge, whether they use it or not, that my approach does in fact produce considerable success for me and my students.  

To the question, then:  When you grade homework, you're not grading students on their knowledge of the material; you're grading the skill of problem solving with new concepts, along with students' diligence in seeking the correct answer.  Fact is, homework (or any work) is worthless if it's not done carefully with a full effort toward getting the correct answer and approach.  "Good faith effort completion" sounds great, but ask yourself -- if you graded students' homework carefully, would they do a better job?  Would they perform better on tests?  

My answer is, I grade homework carefully and thoroughly on a regular basis, especially early in the year.  I grade such that the students expect that their work will be judged, such that the students do their work to the highest standard they can.  And therefore, my students don't have to study for tests.  And, they perform well on those tests, because they've practiced carefully.  The one year when I didn't carefully grade homework, many students did a half-arsed job on the homework, then were upset when their test performance was poor, then complained to all who would listen that physics was too hard and that I was mean and unreasonable in my expectations, that I didn't understand my students.

As for the "fairness' issue, is it fair for the football coach to choose a starting quarterback based on his performance in practice?  I mean, practice is when players are supposed to develop their skills, right, and only the game really matters?  Yes, but everything's a test, everyone is evaluated all the time.  If you grade homework regularly -- even every other night, even only part of one problem, even a grade on a 0-1-2 scale, then you'll have enough data that one bad performance on something a student couldn't grasp quickly will be a mere blip.  

I now am counting homework and daily quizzes as half of the student's term grade, with the other half coming from monthly tests.  Not surprisingly, there is a very high -- nearly 1.0 -- correlation between homework and test grades.  I am virtually certain that the correlation between homework and test performance exists independent of how much you grade, or how much you count the grade.  The goal, therefore, is to create an incentive mechanism so that students do everything they can to get homework right.  Then test and exam performance will take care of itself.  


  1. How do you find time to grade daily quizzes and daily homework? I give homework every night with the solution then I give a homework quiz once a week. I know what you are doing is effective, but the grading is onerous.

  2. DLP, "onerous" is a good word for it. Some options:

    * Give your homework quiz every day, or at least several times a week.
    * Have other students grade the homework quiz
    * Collect homework every night; only actually grade it on nights you have time.
    * Pick one part of one problem to grade, i.e., look just to see if the student used momentum conservation, or just to see if he recognized that one cart moves backwards after collision.
    * Never, ever write comments on homework.
    * No need for consistency -- you can grade thoroughly one night, for completion the next.
    * If you grade a homework quiz, there's no need to grade the underlying problem except for completeness.

    Other thoughts from people? Sounds like this could be a full post. Thanks for the question.

  3. Some questions on your bullet points. I've had a lot of trouble grading even tests in a timely fashion because I can get stuck on details and haven't even attempted homework (do you also not write comments on tests?). -- When you mentioned pick one part of one problem to grade: do you give the entire homework score based on that part of the problem you graded? Do you give parting credit for that part of the problem? Having my students take homework serious has been my main struggle in AP Physics so I would like to try some new things.

  4. I don't write comments on tests, either; I just indicate points earned, and let students figure out their mistake via test corrections.

    The important part of grading homework is simply that there is a number -- a number with some quasi-reasonable correlation with the quality of the work -- on the paper. I can tell you agree that the goal is to get students to take the homework seriously, not to award points on a perfect one-to-one concordance with correct answers. So I do give the entire homework score based on whatever part of the problem I looked at, or whatever aspects of the whole problem I choose to evaluate. Just choose some different aspect of the homework each night; then your homework grading will not be game-able by the students, and they'll just do their best. That's what we want.

  5. What type of homework are you giving for AP Phys 1 and how much per night? I am struggling with the homework.

  6. I'm going through the course once the same way I did AP Physics B -- one or two problems a night, with both calculational and verbal portions. We should get through this material by late January.

    Then I'll go through all the material again, demanding deeper verbal response and deeper understanding. I'll make use of ranking tasks, TIPERs, all sorts of less calculational questions.

    Take a look at my "less is more" article on AP central for some further details of what I do for the first half of the course.

  7. I struggle because I am by nature a follower of the rules and it is against provincial ministry policy to evaluate ("count") homework in the course mark. My work around is open-notes quizzes taken pretty directly from the homework.

  8. I give homework 4 or 5 times a week. I expect the students to do it and I ask them if they have done it. I rarely grade it and if I do I always tell them in advance that I am going to do so. If there is a pattern of not doing the homework, or doing it poorly, we meet and discuss. At my school only the assessment scores count towards their academic grade. There is a separate grade that includes homework completion. Every homework problem goes up on the board or is discussed thoroughly. Students do this. In fact they know they when they arrive at class they can go to the board and start writing. They elbow each other for room! I assign questions to a specific student and their challenge is to explain the question, their methodology, and their final answer.

    I always have assessments graded for the next class. We go over every question thoroughly with lots of discussion. If a student has not earned a passing grade I give them a chance to take another assessment for which they can only earn the minimum passing grade. We have 4 or 5 assessments per quarter. Before I give an assessment I try to give a practice assessment. Many times it is in the form of an inquiry lab.

    I am always fascinated at how teachers deal with these issues. When I told my Dept. Head what I did he was aghast. "If you don't grade homework they won't do it!" he cried. Within a year or two he had adopted all of my ideas :)

    Love your blog, Greg!!