Interesting.
One reason unions usually hate this kind of thing is that ALL of their members aren’t eligible.
For example - if writing and math scores go up, should gym, art, music, home ec etc. teachers get bonuses?
I say “No.”
If students are only tested in reading in 5th and 8th grade, and 8th grade reading scores go up, should the 6th and 7th grade reading teachers get bonuses, or just the 8th grade teachers?