This outline isn't necessarily suitable for all texts, but is likely a useful way to proceed for K-12 texts that need to be designed to meet state content standards.
1. Develop internal integrated content standards, based on publicly available content standards such as:
http://www.cde.ca.gov/standards/science/grade1.html (California) http://www.firn.edu/doe/curric/prek12/pdf/sciencek.pdf (Florida) ftp://ftp.alsde.edu/documents/54/04SciK-2.rtf (Alabama)
The attempt here would be to integrate and harmonize as many of these as is reasonably feasible, including UK and Australian and others as needed.
2. Write texts that precisely mirrors the standards put forward in item #1.
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One thing that this method does is eliminate _our_ need to deal with certain complex questions regarding the proper order of instruction in various fields. Much of this work has been done for us, and if our texts are to gain widespread use, we will need to meet the needs of end users and the decision makers who control which texts are adopted.
The same thing is most likely true for college texts. For example, economics is normally taught in two semesters, Economics 101 and Economics 102. Normally one course is 'micro' and one course is 'macro'. But in any event, to the extent that these courses are pre-requisites for other courses later on, any valid text will need to cover certain points outlined in the course description.
My thinking here is that just as the wikipedia _encyclopedia_ is envisioned as a neutral reference standard, as opposed to an avenue for original research, Wikimedia _textbooks_ should be neutral and tend to avoid original pedagogy.
--Jimbo