Writing teachers probably devote more time to evaluating students than anyone else in education, yet as White ( 1986) noted in Teaching and Assessing Writing, they generally know little or nothing about assessment. This paradox is made even more problematic by the fact that most writing teachers are arrogant about their ignorance. The net result is that, with some important exceptions, such as the training provided by the National Writing Project, writing assessment in the United States may be characterized as chaotic and unprincipled.
Assessing student papers is one of the more important things teachers do because the decisions they make about how they give grades affect students' lives, sometimes significantly. For this reason alone, teachers need to know more about assessment. Reduced to its most basic principle, assessment is a comparison of one thing to another. In the case of student writing, the comparison is made on two levels: Teachers compare the writing of one student to another, and they compare the writing of each student so some pre-established standard of good writing. That standard may be one that the district has established and distributed to teachers; it may be one that the school has established among its teachers; or it may be one that a teacher has developed over the years through experience. The variability of the standard can be a source of trouble whenever there is a lack of consensus. That is, those who are most directly involved in assessment, including students, must agree on the suitability of the standard before meaningful assessment can take place.
Three of the most important topics in writing assessment are: validity, reliability, and time. Validity is related to matching what one is measuring to what one is teaching and to what the assignments ask students to do. For example, an instructor who devotes much of her class time to teaching grammatical terminology but who grades students on their skill at writing autobiography is involved in invalid assessment.