Sunday, March 9, 2014

SBG Targets: Rubric or Checklist?

As I prepare learning targets for my next unit of instruction, I am contemplating whether it might be useful to split my targets into two categories: Checklist Targets and Rubric Targets.  

Checklist Targets would be those for which I need to see evidence students "can do this", without a measure of "how well" they can do it. Here's an example that might make a good Checklist Target:
2.3 I can use technology (e.g. Excel, Geogebra, Desmos, or a graphing calculator) to generate a least-squares linear regression equation for a scatter plot.
There are really only three possibilities:
  1. you can do it correctly, and you've shown me, 
  2. you can do it correctly, but you haven't yet shown me, or
  3. you cannot do it correctly yet.
With a Checklist Target, I would not distinguish between the second and third possibilities; the feedback is the same: you still need to show me you can do this.

A Rubric Target, on the other hand, might allow for varying levels of quality in the submitted evidence. Consider this target:
2.5 I can describe how well a linear model fits a scatter plot both formally and informally, such as by discussing the closeness of the data points to the line and by reporting and discussing the sum of the magnitudes of the residuals.
A student might submit evidence that that lacks detail, contains misconceptions, or shows a partial understanding of the target:
Looking at the line, it appears the points are pretty close, as the figure shows. The sum of residuals is about 12, which is a pretty small, so I conclude that the line is a good fit.
That response would benefit from some corrective feedback (e.g. "You have used orthogonal residuals, but linear regression uses vertical residuals") and suggestions for improvement (e.g. "You might strengthen your response by comparing the sum of residuals for two possible trend lines and discussing which one is preferable").

On the other hand, a response like the following conveys a deeper understanding:
The solid and dotted trend lines produce virtually identical residual sums as my work* shows. However, informally we can see that if the point (1, 5) is removed, the remaining points follow the dotted trend line much more closely than the solid trend line. If we remove that one point and recompute the residuals, we find that the sum of residuals is much smaller for the dotted trend line than the solid one. Therefore, I conclude that the dotted trend line is a better linear model for this relationship.
  * work omitted from this post
A rubric score would help distinguish between those two responses and offer an opportunity for providing feedback and suggestions for improvement.

So it seems I've written my way to a new understanding: in the past, I have used my SBG rubric to score evidence for all of my learning targets. Moving forward, I think I will separate my targets into two types: Checklist Targets and Rubric Targets.

I'll let you know how that goes!

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