Drag & Drop
The order of words in German sentences is difficult because there are many correct possibilities but some options are wrong. Using drag & drop to train suitable word sequences leads to two requests:
1. Please add an option to make an exercise repeatable ("try again") even after a correct solution has been achieved. (This is now only possible by using the "reload" button of the browser - this is a technical solution but no invitation to experiment. Maybe the new option could be named "try another solution".)
2. Allow conditionality: Correct solutions differ depending on whether the sentence is a question or a statement. Make the last drop zone a switch that selects between two or more sets of correct solutions, depending on the punctuation mark that is dropped in the zone.
More simply: Allow a zone with predefined content where nothing is to be dropped. This would then allow to define an exercise as statement or question. The two types could be produced by duplicating.