I'm not a fan of teachers being assessed by students' standardized tests since I don't believe the assessment tell the important story of teaching and learning, however, I do believe that testing and assessments can be used to inform educators about program and teaching improvement and development.
Why Not Judge Educators by Test Scores?
First of all educators are often working without needed supports to teach well. Classes may have too many students. Students may not have the supports they need to learn well, and systems in general may have structures, roles, and programs that don't support good teaching or learning. Of course educators have to speak up for what they need, but often educators' voices are lost in politics, bureaucracies, and more. It's possible that one class can have lots of students who struggle with a number of factors simply because a teacher has a credential to serve those students or because a teacher is good with those students while a class next door could possibly have an "easier to teach" group for one reason or another. Test scores are the result of multiple, complex factors and many of those factors are out of a single teacher's reach so teachers should not be judged by their students' test scores.
Test Assessments Provide Helpful Information Related to Program Development and Improvement
From observing how students take a test to listening to their questions to assessing the results all provide a helpful lens with regard to student learning. As I watch students take a test, I can tell who is willing and able to show what they know, and who is reluctant or unable to figure it out. That helps me to assess who I need to continue to work with to build greater skill and capacity, and it also gives me ideas about where a child is struggling such as need for greater social emotional learning support, need for greater practice and repetition, or need for a different kind of learning and teaching.
Further, as I watch students take a test and listen to their questions, it helps me to understand where students gained good experience, teaching, and understanding, and where I have to revisit to think about how I might change the way I teach a particular concept, skill, or knowledge point. For example today students had many questions about a specific question, and as I assessed, my analysis pointed to the fact that students had not had enough independent practice with interpreting or making the kind of model asked for. I'll go back and teach that concept more in the days ahead.
As we look at the analysis of all the scores, we can determine who made adequate or even better progress and who could have made more progress. This kind of analysis helps us to look at our programs with greater specificity, and that look helps us to think ahead, do some research, and make good changes to better what we do.
So while I don't think scores should be used to rate individual teachers, I do think scores offer one important glimpse into the way we teach, the programs we use, and the development we need to further develop what we do for and with children.