How do I begin?
Since these sentences, from what I can tell so far, aren't translated literally, how am I supposed to know what they are trying to convey without any prior knowledge of German idioms? I'm really lost here.
I posted a feedback suggestion to first show a multiple choice to introduce the idioms.
what about trial and error?
It can sometimes be fun to try and guess the context, like when I saw "Es schüttet wie aus Eimern" it's referring to raining heavily, so I thought it might be equivalent to "It's raining cats and dogs" (turns out it is!). For those that don't have any obvious relation, just skipping them is the way to go - it means it will take longer than usual to complete the lesson, but it also means you will have plenty of practice typing the exact wording of the German idioms and looking at their English equivalents, which will hopefully lead to better retention!
I've also found that looking up the more literal translations of some of the more tricky ones helps to make the connection between the idioms in both languages. For example, I had trouble remembering "In der Not frisst der Teufel Fliegen" => "Beggars can't be choosers" until I looked up a more literal translation; "In times of hardship the devil eats flies". Here is a good resource that has some of them: http://en.wikiquote.org/wiki/Talk:German_proverbs