Most uses for student assessment have little to do with teaching. Most assessment is about sorting students and teachers into bins of success or failure. We test for who will get A’s and who will get D’s. We test for who will get into the best grad school. We test to see which schools are best. These are all useful purposes, but they do not provide guidance as to how to improve our teaching. In particular they provide little guidance for how to tailor teaching to an individual student.
Sorting to the normal curve
We expect that students will perform according to a normal bell curve. There will be excellent students, many average students and some group of less worthy ones. We assign grades, sort students by their GPA and assign them to their lot in life.
The high scores paradox
Sometimes the student scores do not look like a nice bell curve. Sometimes there are many more students getting A’s and B’s. We then puzzle about what this means. Why are all those students getting A’s and B’s.
One assumption is that the assessment is flawed. Somebody lowered the standard. Somehow substandard work is now getting too much credit. This can be easily corrected. We just move the bins so that the appropriate number of students fall into the correct categories.
But what if the original curve was right? What if there was an actual improvement in the teaching and learning? A really great teacher, with motivated students should produce a shifted curve and there really should be more A’s and B’s?
The case AGAINST sorting
In developed economies, the number of jobs requiring little education is rapidly declining. Simultaneously there is a serious shortfall in workers having the skills that education can produce. We actually need the skewed curve. We need a lot more successful students. Assessment for sorting is working against what is best for society in so many ways.
The ugly double-hump curve
In many subjects such as reading, math, computing and science the curve is not the nice tidy bell with an ample group of middle performers. In reality many courses show a double-hump in student performance.
The students who “get it” all perform very well. The students who do not fall way behind. Some of those students on the far left are there because of lack of effort, but many are not.
Many are sorting low because they missed an important skill or concept. Once they missed the skill, education rolled on according to the calendar. Each each time a new concept attempts to build on a knowledge gap a new gap is created. As these gaps accumulate, frustration sets in and eventually the student abandons the subject.
The students on the right of this double-hump curve have been sorted into great jobs and bright futures. These are students who did not miss concepts, were able to repair the gaps on their own or had additional help that filled in what was missing.
Assessment for teaching
Some of the blame for student failure is because nobody knew what that individual student was missing. At the time that it could have been resolved there was no assessment that identified that student’s specific need and no resource to address the specific gap before it caused many other gaps.
Admittedly many such gaps arise due to a student’s lack of effort or interest, but the gaps accumulate none the less. Many of these problems can be resolved by proper assessment for teaching.
If we know what students do not know then we have a chance to fill the gaps before they become unbearable.