The goal is to "convict" students of understanding specific goals or standards, using a "preponderance of evidence" from assessments that probe those goals/standards. Most traditional paper-and-pencil assessments probe simpler knowledge and skills, rather than deeper, structural understanding. Not that a student with real understanding wouldn't do well on them, but it's possible for a student who does well not to have that deep understanding, just by having memorized the surface skills. To probe for understanding, we need to see if kids can apply their understanding to at least marginally new situations. In my classes, this usually results in students complaining (during the test) "You didn't teach us this stuff!" as if they were monkeys trained to jump through a thin blue hoop and completely baffled by being asked to jump through wide red hoop. Getting students past this is a major goal for the upcoming year...
Before I can get there, I need to plan the evidence I'm going to collect. Let me start with the difference between velocity and acceleration (a major stumbling block for many students). What would provide evidence that a student understands the differences?
- Choose correct formula for a situation
- Correctly label a situation (verbal description, video, graph) as constant velocity or changing velocity/acceleration
- Solve traditional problems
- Sketch graphs for constant velocity and changing velocity/acceleration from verbal description, label, or video
- Analyze other rate problems (including the house painting problem)
There's also the idea that assessment should provide a scrapbook, rather than a snapshot, of what students know. Having students assemble the scrapbook/portfolio also asks them to develop their self-knowledge/meta-cognition so that they can recognize good work when they see it. Teaching that is way harder than getting students to recite Newton's Laws...