Grading Systems

I'm not fond of traditional, points-based grading, but I'm not confident with standards-based grading. I've been reading Marzano and Understanding by Design and @DataDiva's rubrics wiki and following the #sbar physics/math axis on Twitter. In an attempt to work out some of the kinks in my understanding, I'm trying to work through not just the curriculum objectives for the course (Basic, CP, and Honors Sophomore Physics all use the same objectives), but also the grading.

The first topic is Constant (or average) Velocity. It doesn't get its own unit in the curriculum: it's part of the Kinematics & Dynamics unit that takes up the entire first semester. Here are the Learning Objectives from the district curriculum:

Learning Objectives

The student will:

• Transcribe raw experimental data into graph form.
• Interpret graphs for physical meaning.
• Show an understanding of kinematics by solving appropriate kinematics problems.
• Distinguish between the position time patterns of constant speed and accelerated motion.
• Show an understanding of dynamics by solving appropriate dynamics problems.
• Apply the concept of inertia to real world situations.
• Explain the relationship between the mass of an object, the forces exerted on it, and the resulting acceleration.
• Identify the equal and opposite force pair which exists in any interaction, including inverse square relationships.
• Handle quantities which involve direction as well as magnitude by using vectors.
• Describe circular motion and the forces necessary to maintain it.
• Become knowledgeable with the universal nature of gravitation and subsequently state its implications.
• Combine kinematics, dynamics and vectors to analyze projectile motions.

Here are the objectives I think apply to constant (or average) velocity problems:

• Interpret graphs for physical meaning.
• Show an understanding of kinematics by solving appropriate kinematics problems.
• Distinguish between the position time patterns of constant speed and accelerated motion.

And now my revisions of those standards into something I hope I can give to students and use as a basis for designing assessments and grading them:

1. Graph experimental data:
3. Create appropriate position-time and velocity-time graphs from verbal or visual descriptions of motion.
3. Solve appropriate kinematics problems:
1. Find average velocity given change in position (displacement) and change in time (duration).
2. Find change in position (displacement) from average velocity and change in time (duration).
3. Find change in time (duration) from change in position (displacement) and average velocity.
9. *Combine skills to solve more complex problems.

I've left out the standards that don't apply. The asterisk marks an "advanced" standard I don't expect my Basic students to reach.

I haven't included the rubric for 3.i., because, frankly, I'm not sure how handle it. It's something that my students frequently have trouble with, so I think I want it in the standards for their consideration, but I don't know how to assess it, other than to throw multi-step problems at them and see what happens. Students who can't handle multi-step problems generally take two random numbers from the question step and stuff them into a formula, which should be handled by the rubric for 3.a.-c., right?


Here are my attempts at 'student' solutions for an old test question:

So, questions: Should I collapse standards a-c into one for feedback & grading purposes? Which rubric should I use? How can I improve the rubrics? Are the distinctions between levels clear? Any other advice?