From the website:
"More than 20.000 grammar and vocabulary exercises
A more than 800-hour interactive online German course
Our exercises are structured according to the European Framework of Reference for Languages"
I have just uploaded a couple of videos onto youtube going through some German grammar. At the moment I have done accusative and dative pronouns and adjective endings following indefinite articles.
One of my Yr 10 students made this grammar tutorial on Relative Pronouns without much guidance from me. This isn't a topic that I normally teach at Year 10 level so I'm very impressed!