All math & science teachers want their students to show their work, but so often students forget/are being lazy/think they don’t need to show their work, especially if they haven’t had a test in a long time.
Just Innocently Grading Quizzes One Weekend…
This weekend I was grading Chemistry tests, and was so frustrated at either (a) students not attempting problems when they know the first few steps, or (b) only writing down their answer to a very long and complicated problem (Stoichiometry). So, I started class today with the following warm-up:
Students pointed out how “6th grader #1” got 1 wrong, but deserves the most credit because they showed the right mistakes, and so showed understanding whereas #2 deserves more credit than #3, even though #2 didn’t get very far on the problem. I even went so far as to claim that #1, in some of my quizzes, and if they demonstrated an ability to do that correctly elsewhere, could still get a 100 because we all agreed #1 understood how to do the problem.
Of course, throughout this discussion, I still had the one or two smart-butts who were convinced that student #3 knew it the best (I’m 99% sure they were just joking), but I don’t think I convinced them to show their work because they “always” get it right (they really don’t…).
Easier to Talk about an Easier Problem
One thing that allowed us to have a discussion about understanding is that the math was easy enough for all the students (juniors in HS) to solve, so if you were trying to convince 6th graders to show their work, this might not be the first choice. If I had chose a Stoichiometry problem (complicated Chemistry problem) to demonstrate “why you should show your work” then I think my students would have gotten lost in the mechanics of the problem and not seen the bigger picture. Now, I hope that my students will not forget to show their work in the future.
How Do Get Your Students to Show their Work?
So I guess this took 5 minutes out of class in place of a warm-up (I had another warm-up after that one), so it did not take a lot of class time. However, it helped tremendously that my students were used to my quizzes (which I think they recognize as testing understanding and not “how many you got right”), and it helped to have the discussion right on the heels of a test where students can think about what they did wrong and learn from their mistakes. Would this discussion have the same effect at the beginning of the year? How do you convince your students that work is important? Does it work? Or is it a constant battle?
Hilbert's Hotel 
One of the things I have started doing (in my 26th year now) is finally caving into a bit of the bribing culture. On certain questions where I have not been as clear as I need to be about what work MUST be shown, I will give a student an extra point here and there for clear and thorough work shown. So, a student may earn 6 points on a 5 point question or may earn full credit with an incorrect conclusion but solid work throughout (like your hypothetical student #1) Although I would hope that they realize one extra point here and there makes little ultimate difference, it is a powerful motivator – especially in harder classes where mistakes are more often made.
That’s a good idea. Do you find that all students take this up? Or only the ones “who don’t need the extra point”?