Having discussed the difference between "als" and "wenn" in German, the other two subordinate clause conjunctions that students struggle to comprehend are "um...zu" and "damit". So what is the difference, and how do we use them?
Subordinate clauses with "Um...zu" (in order to) don't have a subject because it is assumed to be the same as in the main clause and carry the infinitive of the verb to the end of the clause, while subordinate clauses with "damit" (so that) do have a subject- and one that can be different from the subject in the main clause- and send the conjugated verb at the end of the subordinate clause.
Let's first take a look at the same sentence using the two different conjunctions.
Ich lerne Deutsch, um mit meiner Partnerin auf Deutsch sprechen zu können
Ich lerne Deutsch, damit ich mit meiner Partnerin auf Deutsch sprechen kann.
The meaning of the sentences is the same- both communicate an intention. Yet grammatically "damit" is a classic subordinate clause conjunction in the sense that it is followed by the subject and sends the conjugated verb to the end. "Um...zu" doesn't follow that logic. "Um...zu" clauses don't need a subject because it is assumed to be the same as in the main clause, and the "zu" is followed by the unconjugated form of the verb.
While it is grammatically correct to use the two conjunctions as I do above, the point of "damit" is that should be used in situations where the subject in the subordinate clause is different from the subject in the main clause.
Ich lerne Deutsch, damit die Eltern meiner Partnerin mich besser verstehen.
So whenever the subject in both parts of the sentence is the same, use "um...zu". When it is not, use "damit".
Learn more about German word order in main and subordinate clauses on my blog. There, you will also find posts about the difference between nachdem and danach, bevor and vorher, when to use zu in German sentence, an explanation of how to use um...zu and damit, and a post about the use of als and wenn in German.
On our blog, you will also find posts about adjective endings in German, and the German cases on our blog. There, you will also find reviews about the most common online German dictionaries and apps for learning German.