1.- The software is logically structured and easy to use by children.
2.- The different levels of difficulty can be adjusted (easy-medium-hard) and thus can be worked through from cover to cover the corresponding block (for example "light"). With other software you have to exercise a block in all levels from easy to hard work through succession to the hoped-for "reward" to receive. So it happens with Duden not that one must tell the child: "Here you can go on for another few months."
3.- The user interface is always similar, regardless of whether you do or German mathematics. Thus, the children find their way immediately, if they already know Duden software.
4.- The software is installed on the hard drive and you do not need to perform a CD- or DVD-ROM in the drive.
5.- The software does not require administrative of "player" rights! And this is one thing that does not note many programmers when programming games and educational software for kids.
6.- The program also runs on other drives and in other directories and as just under C: \ Program Files \ ...
7.- The "Score" stores off continuously and automatically. So there are no problems here.
8.- The children love to work with the software, it does in this case, fun to learn something; and what you want as a parent more.
Negative points not occur to me now, but I will if necessary complement.
Thus, this software is a good way to practice the learned in school and deepen. I can only, as has been the 1st part, highly recommend.