There is an epic struggle going on now over assessment in (and out of) schools.
The essential struggle is assessment for a last century factory age versus assessment for the knowledge society of the 21st century. But here's the basic struggles:
*Subjective versus Objective
*Teacher versus Third Party
*Behavior versus Learning Only
*Bias in favor of Females versus Gender Neutral
Here's a battle that has already been won by the 21st century: benchmarks have won over grading on the curve (comparing one student to another).
Stay tuned as the conflicting research and studies seek to justify one side or the other, until society and education finally goes with the 21st century around (you guessed it) 2020.