what are 4 reasons for which a tenured teacher may be dismissed?

Answer 1

immorality

incompetency

insubordination

illegal activities? (I forgot the last one)

Answer 2

It probably varies from state to state and even district to district, but in general I would say one-time offenses would most likely be intoxicated on duty, inappropriate touching, etc. with a student, and physical abuse, although as a teacher for 15 years, I've seen cases where even these did not result in dismissal. In most cases where lesser offenses are an issue, administrators must document a consistent and fairly long-term pattern of insubordination, incompetence, ineffectiveness, etc. to terminate a teacher.

Answer 3

Incompetency for one.
I worked at a district where the principle was retiring that year and so he didn't notice that one of his new hires ( a special ed teacher) was yelling at the kids and telling them they weren't trying and punishing them by giving them extra homework that was at grade level, but didn't have any allowances for them being in special ed. She would also humiliate (in my opinion) students by taking them out in the hall and belittling them and yell at them for not being smarter.
Several of us teachers aides spoke to the lead special ed teacher about it and she said she knew about it and was talking with the teacher and the principle about it.
Later we found out her contract was renewed because no one gave specific examples of what she was doing and no one documented what she was doing. She was later transfered to a middle school elective class. (I'll get off my soapbox now)

I would think other reasons would include inappropriate contact with a student, insubordination, taking too many days off (used all of sick and personal time and still taking days off).