In teaching, the subject matter to be taught that year is laid out in a syllabus, but I don't think that includes administration tasks.
We do use "work plan" in my employment (UK government) to refer to a plan of specific tasks that will be carried out over a planned period of time, and this seems to be an accepted term. A lot of the Google results turn up project-related definitions, but likely only because that is an area where they are heavily used.
A 'Job Description' (sometimes abbreviated to 'JD') is a document that details the various tasks and responsibilities within a role, but it will not detail the specifics such as the subject matter a teacher will teach that year, so I don't believe this is what you are looking for.
A technical term commonly now used to describe instructions for a specific task at work is 'SOP', which stands for Standard Operating Procedure. However, a SOP may include the work of more than one person, or just part of one person's role, so this also may not be suitable.