Another option to practice your German skills is the Online Deutschkurs at www.deutschakademie.de/online-deutschkurs. Here you can choose more specificly what do you want to work on it.
– Do you want to practice according to the levels of the Common European Framework of Reference for Languages?
– Do you want to do exercises from the German course books? There is a list of 70 German course books.
– Do you prefer to work on specific grammar topic?
The exercises are multiple choice. You can see if your answer was correct or not and which is the correct answer. At the end of a pack of exercises you can see again all the questions, one after each other with your answer and the correct answer.
This course is also available for Android Smartphones or Tablets. The App is for free, yo can downtload it and do an exercise in the Ubahn, waiting for the S-Bahn or before the Opera play starts!