Grades are Worse Than a Blurry Surveillance Photo

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Calhan High School Senior Classroom By David Shankbone [GFDL or CC-BY-SA-3.0], via Wikimedia Commons

Calhan High School Senior Classroom By David Shankbone [GFDL or CC-BY-SA-3.0], via Wikimedia Commons

If you watch shows like CSI and NCIS, you’ve probably seen a scene like this one where the investigators discover a blurry surveillance photo and use it to find out critical details about the perpetrator:

“Sure,” the fictional technician tells you, “I can zoom in on that picture and enhance it to see the detail.”

But of course, in real life this is impossible. A digital photograph is just a collection of pixels, each of which is a single data point of color. Zooming in just makes the square bigger.

Regular readers of this blog know that we at Brilliant or Insane want to abolish grades in schools. Grades hurt students and distract them from real learning.

But if you’re still not convinced, consider this. Grades are even worse than those blurry “zoom and enhance” surveillance photos in CSI. Grades actually eliminate information and make it impossible to see any meaningful learning detail about a student.

Here’s a photo I took last fall in Sedona, Arizona. The image below is scaled down to fit on the page, but if you click on it, you will see the original photo at full size so you can see all of the detail.

sedona-original

Here’s the same photo, but this time, I only attached the scaled-down version. If you click it, you won’t see any more detail. In fact, if you zoom in, you’ll just see blocks of color.

sedona-300

I can scale the photo further. The advantage is that the file is much smaller and it’s easier to transmit. The original picture is over 2 million bytes. It is 250 times bigger than this tiny version. When you look at it, you can still recognize the original photo in the colors and shapes.

sedona-20

But if I enlarge it again, this is what you see:


sedona-20-zoomed

Each pixel in the reduced photo is essentially the average of a whole group of pixels in the original. It’s still enough for our brain to make out the gist of the photo, but we’ve lost all of the detail.

Now imagine that the original photo represents a student’s high school career. Each original pixel is a different learning activity or experience. Every time you summarize a group of those activities into a single grade, you are shrinking the photo, reducing the detail.

Now let’s take that student’s high school career and boil it down to a transcript. Just the final grades for each course over four years:

sedona-5Too small to see? Here it is larger:

sedona-5-zoomed

And what happens if we only consider the student’s GPA? Well, you wouldn’t even be able to find the photo unless I blow it up. Here you go. If you’ve ever been to Sedona, I’m sure this brings back as many wonderful memories for you as it does for me. Enjoy.

sedona-1

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Gerald Aungst

Supervisor of Gifted and Elementary Math at School District of Cheltenham Township
Gerald Aungst has more than 20 years experience as a professional educator, specializing in digital technology, mathematics, and gifted education. In his various roles as a classroom teacher, gifted support specialist, administrator, curriculum designer, and professional developer, he has worked to create a rich and vibrant learning culture. He is also passionate about improving learning opportunities for all students. Gerald is a founder of AllAboutExplorers.com and ConnectedTeachers.org.
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