[jetti]

Some schools/districts do that. It turns out though, that many teachers want to control their own classroom and do their own plan. One of the gripes my fiance had while student teaching and then subbing was that she wasn't in control of her lesson planning. One of the issues with the Chicago Public School strike was that the teachers weren't able to create their own lesson plans.

Standardizing the lesson plan eliminates (or greatly reduces) the ability for the teacher to be creative in their classroom and teaching. On top of that, a standardized lesson plan would also be hard to work around in case there were areas that took the students longer than expected.