Somewhere in the science standards for your state, it probably addresses the ideas of accuracy and precision. If you Google these terms, you’ll see countless articles, videos, examples, lesson plans, etc. Let me give you a really basic summary.
Accuracy is how close a measurement is to the accepted/desired/expected value. Precision is how close together each measurement is to the other measurements.
Assume for the following example that my car’s speedometer is properly calibrated. If my speedometer reads 65 mph and I pass a speed limit sign that measures my car’s speed and it says 65 mph, the measurement seems accurate. If I pass that same sign while going 65 mph five days in a row and it reads 65 mph all five days, I assume that the sign is both precise and accurate.
If I were to pass that sign at 65 mph and everyday it read 83 mph, it would be precise, but not accurate. If for five days I passed that sign at 65 mph and it read 43, 60, 11, 99, and 3 mph, it would be neither accurate nor precise.
Now to education.
An assessment might be a precise measurement tool: a student with a specific ability level might score the same over and over.
An assessment might be an accurate measurement tool: a student who has an expected ability level might receive a score that matches that level.
But neither of these really captures the most important aspect of the assessment: is it measuring something we actually value or just something that is easily measured? A cursory knowledge of photosynthesis or an understanding of our place and impact on this planet? Solving for congruent parts of triangles or financial literacy and the long term consequences of mismanaging credit? Understanding the mood of an epic poem or being able to evaluate the legitimacy of a source of information? How to sit still and quiet in a room for hours on end or how to properly manage your attention in a world full of distractions?
This post was based on a quote from an episode of the podcast Freakonomics, where Dr. Mitchel Resnick (a professor of Learning Research at the MIT Media Lab) stated the following, “Schools end up focusing on the things that are most easily assessed, rather than focusing on the things that are most valuable for kids and valuable for thriving in today’s society. So what we need to do is to focus more on trying to assess the things we value rather than valuing the things that are most easily assessed.” Thanks to @mres (a fellow ISTE Making It Happen Award Winner) for the inspiration.