Nate at The Proletariat has a worthwhile post on how the metric of individual merit present in most (all?) proposals for instituting merit pay for teachers fails to recognize the collaborate reality of our schools.
Excerpt (full post here):
In the beginning of the school year you are likely to see ESL, Title, and Reading Recovery staff all chipping in to assess children in reading. You are also likely to see Title staff in your room delivering instruction along with the classroom teacher. It is also highly likely that in order to meet the academic needs of other students, a teacher will send students to other classrooms, and other students will come to yours.
This sort of collaboration is not limited to reading, but also occurs in math, science and social studies. It is that old Vygotskian proverb that the interaction or process of H20 can not be explained by isolating the individual elements. Isolating a classroom teacher from their larger ensemble or school culture is akin to examining a fish out of water. Meritocracy will discourage all the behaviors that educational school reform has been based on for the last ten years. Teachers will become resistant to collaboration with other teachers and staff which has been so essential to student progress.
This is yet another reason the business models for education reform don’t make sense.
Thomas J. Mertz