Ironically published in a closed and massively over-priced Handbook of IT in Primary and Secondary Education, here's a chapter from me and Gerald Ardito on open and distance learning in the context of teaching children (paywall). I don’t know very much about primary and secondary education per se, but Gerald knows a lot, and we share a lot of attitudes, interests, and practices relating to education in general, so it was fun authoring this with him.

In the chapter we characterize openness as freedom from constraint - the more there are constraints, the less open it is, on whatever dimension of openness you choose to consider. The insight that pleases me most in this chapter is that, as applied in adult education, openness has traditionally been about making it easier to get in, whereas in child education the problem lies in making it easier to opt out, whether of a specific school or of the curriculum requirements imposed on it. In the chapter we use this as a foundation to explore dimensions of openness, kinds of openness, and ways of escaping the pedagogical constraints of traditional teaching systems.  

One thing that is important to observe, and that is implicit in our chapter, is that this simple characterization hides a wealth of complexity, nuance, and fuzziness. Most adult learners who are enrolled within an educational system have a great many constraints that prevent or discourage them from getting out of it, or at least out of the chunk into which they have enrolled, and most child learners have a great many freedoms, often including things we do mention in the chapter like homeschooling and (sometimes, though often dependent on income or religious persuasion) alternative schools of many varieties, but equally within the structure of traditional schooling itself. However, as a general pattern, it seems to me that any system that demands attendance, especially where even the alternative choices are themselves constrained in the extent to which they are allowed to depart from a fixed curriculum, cannot be accurately described as particularly open, any more than one that erects barriers to attendance or that unnecessarily limits how and what is learned within it. An open prison provides fewer barriers to leaving it than a traditional prison, and may allow greater freedoms within its boundaries, but it is still a prison.

Openness, however, is not so much about freedom as it is about control. There is often less than no point in removing barriers to choice if the learners do not know what to choose or why to choose it. A large part of the essence of being in control therefore lies in our ability to delegate choices to another. This is exactly how all powerful people are powerful: they are able to exercise influence over others who will do what they wish to be done to achieve what they wish to achieve.

I believe that a central and fundamental goal of education is empowerment of learners. Consequently, anything that disempowers learners is almost certainly a bad thing (exceptions apply only when the needs of one conflict with the need of others), and anything that eliminates barriers is a good thing. This is why there is a moral imperative for all educators to seek openness in all that they do, whether in terms of access, pedagogy, engagement, content, or whatever, and to eliminate barriers to learning whatever form they may take. Education empowers. Openness empowers education.