Common Core - introducing standards-based education

I have had a few comments on my Common Core posts showing a misunderstanding of standards so I think I should explore what is going on.

Teacher Appraisal or Evaluation

A California court has struck down their teacher tenure rules as being "unconstitutional". Apparently, bad teachers are protected by tenure and so it follows that students of these teachers do not receive the education guaranteed under the state's constitution. Considerable public discussion has included assertions of "bad" teachers and "bad" teaching, presupposing a mechanism for determining "bad".