Learning is not Pass/Fail
Years ago I worked with a colleague in the research office of a major school system. He always tried to find a way to make research and statistics understandable to the average person. He once talked about the infamous College Acceptance Letter. I'm not sure if this is still true today, but years ago you would apply to multiple colleges and then you would wait and wait and wait for a letter from these colleges that would tell you whether or not you have been accepted. When the letter arrived, you would open it and there would be one or two paragraphs of "welcome" and "thank you" messages. And, finally, somewhere halfway down the page you would get to the part that you really wanted to know: Accepted or Not Accepted.
My colleague suggested that the most important information in such a letter should come in the very beginning and the other stuff can be written farther down in the letter. Better yet, he suggested, they should just send a letter with a smiley face or a frowny face! That would be the simplest way to communicate the message and everyone would understand what it meant.
I wonder if people outside of education often view learning in the same way? "You get it." or "You don't get it." We sometimes use the phrase "Filling your brain with knowledge." I wonder if some people imagine learning to be this (sort of) empty skull or glass that is filled by the teacher. When it is full, then you have learned it and you got it and you will always have it.
In reality, learning is much more of a process with a somewhat hazy finish line. While there are certainly facts that students can memorize (5 + 5 = 10; July 4, 1776 is the date of the signing of the Declaration of Independence; Paris is the capital of France), actually learning is much more of a process that develops over time and requires thinking and discussing and trying and failing and trying again--and learning from the mistakes. Learning is much more like a baby learning to walk than it is like a switch that is off or on.
We should think of learning as being more of a continuum and less of a Yes/No, Pass/Fail dichotomy. After all, it isn't so much that we want our children to "pass" in school; what we really want is for our children to "learn" in school. Employers don't care what grade you got on a test in high school. They care about what you learned and are able to do.