Question

I work in K12 Education and have been a firm believer in the damaging
effect of using zeros in the grading process. However, to better
understand some of the opposing perceptions I went to a workshop
session and it has shaken my beliefs. One point the presenter made is
that there is a lack of research that supports the assertion that the
use of zeros is harmful or even ineffective. He states in his slides
"Nozero advocates regularly cite Thomas Guskey for their claim that
zeros and/or low grades make students withdraw from learning...
Guskey’s key argument against zeros is based on one English teacher’s
opinionbased presentation at a conference almost 20 years ago.
Interestingly, Guskey repeats the same claim about zeros in several of
his books and always cites the same presentation by Raebeck."
I have done some looking for further research, but I was hoping you
might be able to provide some comments and point me to some sources of
research about the negative effects of using zeros in assessment and
grading. Thanks for your time.

20150829 Robert B 

The Grade Doctor says:

Sorry for the delay in replying.
You obviously went to a workshop given by the one and only Michael Zwagstra who
seems to want us to return to the schools of the 1950’s. It isn’t lack of research “that
supports the assertion that the use of zeros is harmful;” it is logic and the correct
application of mathematical principles that provides the reasons why zeros should
never be used when grades are determined/calculated based on a percentage scale.
Zeros are used as punishments most commonly for missing “work”/ assessment
evidence. In Canada this occurs in provincial systems where teachers are required
(sadly) to provide a percentage grade for each subject and, while there is some
variation, the most common scale used is A = 80100%, B = 7079%, C = 6069%, D
= 5059% and F= below 50%. This is an unequal difference scale and given that there
are 10 points for B’s, C’s and D’s it means that a zero is the equivalent of a K and I
doubt that you or anyone other than Zwaagstra would advocate that we give students
K’s. The problem is compounded by the fact that the most common method of
calculating grades is the use of the mean. We usually teach about measures of central
tendency in grade 5 and we teach that the mean is skewed by outlier scores and that
it is not the mathematically correct measure of central tendency when there are
outliers. My main argument against the use of zeros is that it is professionally and
ethically necessary to do in our grade books what we teach our students in math
classes and so using an zeros in an unequal difference scale where we use the mean
to determine grades is morally unacceptable. In addition to the ethics of the use of
zeros they are harmful because they distort the summary picture of student
achievement provided by grades.
Zeros are also inappropriate because of their impact on motivation. After one zero a
student needs nine perfect scores to get back to their real level. Several zeros means
that students have no possibility of success and this obviously will lead to students
goving up – and often becoming a discipline problem – or a dropout.
The other main point that I would make is that using zeros basically says to students
that they don’t have to do the work and this is the opposite of accountability;
accountability is doing the work on time – or later.
