If the most effective teachers work in properly structured schools with leadership support for professional learning communities (which can entail interdisciplinary as well as subject-based teams of teachers working together to help each other and students improve), then it stands to reason that individual performance pay would have two obstacles to overcome in its implementation, especially in the upper grades.The second obstacle Wallace suggests, I had thought about, but I have not given much thought to the first. While it may be possible in some subjects, say math or science, to divorce one teacher's effort from anothers, in others, such as reading or writing, it may be impossible to separate one teacher's effect from the collective effect.
First, it would be very difficult to divorce each teacher’s effect from the collective effect. It could be done, I suppose, but overall I think that having that many teachers in the equation would dilute the concentrated effect I see operating as an underlying assumption of how merit pay would work. Second, I can’t help but worry that as significant, individual bonuses become the incentive, some teachers would be compelled to avoid collaboration. (emphasis added)
Of course, that could be a problem, but the reverse is also true. Suppose a school had a solid corps of good teachers but one or two were of such poor quality that their negative impact on student achievement creates a drag on student achievement. So if single teacher merit pay might produce an incentive to avoid collaboration in order to maximize personal gain, collaborative or group bonuses would create a free rider problem, where the efforts of a small corps of excellent teachers can boost the performance of a larger group of mediocre or poor teachers, or conversely the poor performance of one or two truly poor teachers can reduce the chances of a group bonuses, how do we manage the avoidance of a free-rider problem?
In the end, I think we are likely to see an amalgamation of merit pay, with individual teacher bonuses, group bonuses within a school and school based bonuses.