In the corporate world, we never fired a person right off, for not accomplishing their job...
turn over of employees is costly...
and we didn't want what we had to contribute to the gov'ts unemployment fund to go up with too many firings,
plus we felt we hired the person because we felt they would be assets to the company, so we always spent some time with them, training or re-training in the areas where they were weak...
we gave 3 chances, spent time showing them how to do it right...
then after 3 strikes, they were OUT.
Same should be done with teachers...and maybe it's admin/principles that sit on their tushes instead of overseeing and training, where it is needed/lacking, that is the problem?
Personally, I think most all teachers are good teachers, it's the children and parents of these children, that make jobs much harder for teachers in our day...