From comment 7 it looks like you have repositories correct, but dpkg still tries to configure a half-installed version.
So first try to remove schooltool
$ sudo apt-get remove schooltool python-schooltool
From comment 7 it looks like you have repositories correct, but dpkg still tries to configure a half-installed version.
So first try to remove schooltool
$ sudo apt-get remove schooltool python-schooltool