Thanks yynotdivein, I agree that Zahra was unlikely to have been truly home schooled by EB. For me there's more curiosity in the motivation for this decision, rather than in whether it ever occurred. Do we know if EB home schooled her other children? I find it hard see it as an idea of Adam's alone, which is why I previously considered other reasons (as mentioned in the other thread) as to why Zahra was taken out of school.
If we determine that EB was responsible for this idea, I'd still think it very strange. What seemed like a good idea at the time would have very quickly turned sour, IMO; as per my post on the previous page where I outline how I think this decision put Zahra at risk because of the ways EB would likely react to these circumstances and responsibilities.
Another thought if we consider tlcox's suggestion that Adam was planning to leave, and consider that AY stated this (I have also posted that I think this is plausible), then I wonder if he thought taking Zahra out of school was a good way to disappear unnoticed away from EB and back to Australia with Zahra. It's all speculation I realise, but if this was true, maybe EB found out (eg saw the passports in the car) and retaliated by killing precious Zahra as punishment to Adam for having the audacity to leave her? It's a bit out there, I know, but who knows, it could be true! We don't know what they knew of each other's plans, or what they argued about in weeks/months leading up to Zahra's death.
Re: schooling systems, thank you for providing a good basis for comparison of systems. Sounds like our school options are similar in the context of organised schools, though not the less common home school option. Certainly the cost of private schools (confusingly known as "public schools" as per the English model of non-exclusionary education) $35,000 a year for tuition (+ uniform, equipment, books, camps, etc) for our top schools. The years at school (kindergarten + 13 years) + university (undergraduate 3 years > + 1 year for honors > Masters > PhD) is a little different, and school curriculum is also; however, we are undergoing a phase of experimentation University of Melbourne is running a trial with an intermediate year before the fully-fledged undergraduate course, which we understand is based on the American model. Within our system we also have curriculum variations such as Rudolph Steiner models and International Baccalaureate (which I assume you also have in the US).