Teachers usually prepare their classes at home, so they need the same software there that it is installed at the school they work in, with the same version of any app. As they do with books, teachers need to make agreements on the software they install in computer labs. This is not just a pedagogical, but a technical and a management need. This is the first problem the have to face.
In Spain, due to political reasons, regional governments are in charge of the technical issues that deals with computers involved in education. So they select most (or all) of the apps you find in a computer lab of any public school. This is one of the reasons we have been so successful in promoting free software at schools. It is a political decision and teachers support it (although it takes time). But other countries do not have global solutions for this, since each school or teacher have independence for choosing the applications to work with at school. This is not an advantage from a managing or a supporting point of view (it doesn’t have to be a disadvantage either if there is a good coordination).
Let’s assume that this problem is solved.
Supporting the software and creating documentation around a single app is hard to do and takes time. To teach teachers and students to use the software chosen takes a while too, so it is impossible for edu projects to follow short release periods, as software libre distributions do. They soon get out of date, unsupported. So teachers and students end up having at home newer versions of the software they have at school. This is already a problem for those teachers that already have good skills using linux.
In addition, each distro have its own politic related with repositories and versions of packets they include and support in any release. Even if a single (or group) of schools follow it, still there is a problem with what people have at home.
One of the things that should be done by schools or regional govs. in order to reduce the impact of this problem is to create and maintain their own repository of packets to ensure they all use the same version of the same app they have at school. This is a good point for students also.
In my opinion, this repository should be distro independent, so teachers (or students) can install the distro they want (from the official distro repository, or from a installation CD), and add this edu repository, so they have the same version of any app. This can also include Windows versions of edu apps. This doesn’t work at 100% but there are technical ways of getting close.
This is a better approach than preparing a complete edu distro and having to support the installation process, hardware drivers, desktop configs, etc.. Distros already take care of that and they do it well because they have the experience.
What makes the difference if you use KDE, and I think the best thing this can be done, is to be able to download and install from the edu repository the profile (configured with kiosk mode) you have in school (if you use KDE), with all the apps, so teachers have the same configs and apps in a semi-independent desktop.
By doing this, what people in charge of edu projects can do, is to put more effort on spreading their experience selecting and configuring the desktop (improving usability), on promoting a community around the software they install and on connecting that community directly with distro, desktop and apps communities, instead of putting so much effort on technical stuff related with live CD installation, hardware configurations, release periods etc. in uncontrolled environments. To deploy, update and maintain the software on computer labs and other dependencies in schools (controlled environments) is already a huge project that takes many resources.
This is not the politic big edu projects are following in general. They are promoting that people at home install the same complete distro they have at school, adding an unsustainable and non scalable effort to the technical people they have. That politic have to change if we want to give response to the increasing demand we gonna face during the following years. Specially, if computer stores begin to sell machines with linux preinstalled, so regular users won’t have to install that whatever linux operative system they (or the store) choose anymore (probably different than the one they have at schools).